The CSS Solved General Science & Ability (GSA) Past Paper 2019 is Solved by Pakistan’s top GSA Coaches, Miss Iqra Ali and Sir Ammar Hashmi. They are the only coaches available in Pakistan who have solved the last 20 years’ GSA solved papers to help aspirants know how to attempt the paper to score above 80. And they have guided thousands of CSS and PMS aspirants. Both coaches have been known for their teaching methodology and imparting concepts to their students, who scored the highest marks in this subject. At the special request of CSSPrepForum, both coaches have solved the paper.
Question – 02
(A) Deficiency of vitamins causes different human diseases some of which are given in the table below. Choose
Question Breakdown:
In this question, the examiner has simply asked you to put the correct form of vitamins in the already given table and write them down in front of the diseases which these vitamins cause if there is a deficiency of these vitamins in the human body. Simply draw a table in your answer sheet and put them accordingly. Remember, some questions are so simple that no creativity also becomes creativity. Thus, do not try to write too much when the question being asked is very simple.
Answer:
| Disease caused due to lack of Vitamin | Name of the Vitamin |
| Poor Night Vision | Vitamin A |
| Bleeding Gums | Vitamin C |
| Rickets in Children | Vitamin D |
| Beri-Beri | Vitamin B1 |
| Anaemia | Vitamin E |
(B) People suffering from cardiovascular diseases have a high level of cholesterol in their blood. This often leads to a build-up of fats on the internal arterial walls. Suggest how this might be harmful to the heart.
Question Breakdown:
In this question, the examiner has asked you the consequences of cardiovascular disease. First, describe the cholesterol in your own words briefly. When done, hit the topic straight without going into the detail of the diseases with symptoms and causes etc. Although you do not need to draw any diagram in this question, making a relevant diagram can help you get maximum marks.
Answer:
Cholesterol:
Cholesterol is a fat-like substance belonging to the class of organic compounds named lipid. Inside the body, it is produced by the liver, and its external intake sources include egg, milk, and meat due to its importance in maintaining the structure and function of the human cells-the basic unit of life.
High Level of Cholesterol and Cardiovascular Diseases:
However, if the cholesterol level in the body is raised from normal, it can be a severe risk factor for multiple heart diseases that include:
1. Atherosclerosis:
The building of plaque in the vessels is called atherosclerosis. The arteries supplying blood from the heart to the body become narrowed and blood flow to the heart muscle is slowed down or blocked.
2. Ischemic Heart Disease:
When arteries are narrowed due to atherosclerosis, less blood and oxygen reach the heart muscle. This is also called coronary artery disease and coronary heart disease. This can ultimately lead to a heart attack.
3. Arrhythmia:
Arrhythmia or irregular heart rate is another heart anomaly that is caused by the blockage of heart vessels, that is, in return, due to raised cholesterol levels.
4. Heart-Attack:
Having too much cholesterol in your blood can cause fatty deposits to build up in your arteries. This can make the arteries narrow and stiff, making it harder for blood to flow, causing heart-attack.
5. Heart Failure:
Heart failure means the heart is unable to pump blood around the body properly. It usually happens because the heart has become too weak or stiff due to the raised level of cholesterol.
(C) Why the excessive use of chemical fertilizers should be avoided?
Question Breakdown:
In this question, the examiner has simply asked you to write down the reasons why one shouldn’t use chemical fertilizers excessively. First, write down what the chemical fertilizers actually are in your own words. When done, write down all the possible reasons behind avoiding their excessive use. Lastly, you do not need to draw any diagram for this question.
Answer:
Chemical Fertilizers:
Chemical fertilizers are substances containing chemical elements that increase the fertility of the soil and improve the growth and productivity of crops.
The Need for Chemical Fertilizer:
Plants require a number of nutrients like sulfur, nitrogen, and phosphorus for their growth. However, soil nutrient levels can decrease over time when crop plants are harvested. Hence, these essential nutrients need to be compensated either through the natural process of decomposition, when plants die and decay, and the nutrients extracted from the soil return to the soil or by the easy means of adding fertilizers.
Hazards associated with excessive use of fertilizers:
Although chemical fertilizers are no less than a blessing for human beings, their excessive uses are associated with numerous hazards.
- Chemical fertilizers affect microorganisms living in the soil by disturbing its pH more acidic.
- Such kinds of fertilizers are highly soluble in water; thus, they leach away from the soil without benefiting the plants to their maximum.
- Excessive nitrogen used in the chemical fertilizer can emit greenhouse gasses into the atmosphere, contributing to environmental pollution.
- Since the fertilizers are chemical based, their inappropriate can cause eutrophication- the phenomenon of accumulation of nutrients building a layer of green algae over water resources that endangers the existence of aquatic life.
- The excessive use of chemical fertilizers depletes the soil of natural essential nutrients. Consequently, the produced foods have less nutritious value.
(D) Why are scientists worried about the increase of Carbon Dioxide in the atmosphere?
Question Breakdown:
The examiner has simply asked you to explain, in detail, the causes and reasons why the scientists are worried about the increase of co2 in the atmosphere. Start your answer with a description of the reasons briefly. When done, mention the functions that Co2 performs in the atmosphere. Moreover, write down the causes for its increase in the atmosphere followed by the consequences that it can have on our planet. Lastly, draw a diagram showing its cycle of being absorbed and re-release in the atmosphere i.e., the Carbon Cycle.
Answer:
Carbon dioxide is responsible for the enhancement in the ability of the atmosphere to heat. Moreover, the presence of carbon dioxide in the earth’s tropospheric zone raises the temperature of the earth’s atmosphere. Consequently, it can have devastating outcomes for the inhabitants of the planet earth i.e., global warming and climate change. Thus, scientists are worried about the increase of CO2 in the atmosphere. To understand the concept, it is very important to first understand the function of CO2 in the atmosphere as well as the causes that are responsible for its increase.
What is the main function of CO2 in the atmosphere?
CO2, being the most important greenhouse gas (GHG), helps in trapping the heat in the atmosphere. One can say that without CO2 our planet would have been inhospitably cold. Without it, Earth’s natural greenhouse effect would be so feeble that it would be impossible to maintain its average surface temperature above freezing as it absorbs and holds the energy and heat it receives from the Sun in order to stop it from escaping back into space and re-release it in all possible directions. Without it, Earth’s ocean would be frozen solid.
What are the causes that are responsible for the increase of CO2?
Because of the role of CO2 in climate, feedbacks in the carbon cycle act to maintain global temperatures within certain bounds so that the climate never gets too hot or too cold to support life on Earth when this cycle gets disturbed due to some anthropogenic activities. These activities include:
- Burning of fossil fuels
- Use of other non-renewable energy resources
- Deforestation
- Industrialization
What are the possible consequences that are making it a huge concern for scientists?
Extreme Weather Conditions:
Rising temperature has drastic impacts as it can cause:
a. Melting glaciers
b. Floods and flash floods
c. Droughts leading to famine
d. The rising sea level -is an existential threat to human survival
Global warming and Climate change:
Not to speak of the aforementioned impacts, this staggering increase in the level of carbon dioxide in the past few decades is of great concern to scientists because of the phenomenon of global warming and climate change. According to NASA, an increase of 1.5 degrees Fahrenheit in global temperature has been recorded which has made 2021 the 6th warmest year in the continued trend.
To sum it all up, with carbon dioxide enhancement in the atmosphere, the temperature has increased to an alarming level that has become a formidable challenge for the only inhabitable planet Earth.
Question – 03
(A) Differentiate between the Renewable and Non-Renewable sources of energy giving examples of each one of them
Question Breakdown:
The examiner, in this question, has simply asked you to highlight the differences between renewable and non-renewable energy resources. The very first and foremost thing that you need to do is to draw a table with two columns in order to draw a comparison between the two terms. When done, start your answer by defining both the terms as your first point which should be followed by other main points of comparison respectively. In the very last box of the table, give examples for each of them. Remember, being creative is what will award you maximum marks on your GSA paper. Lastly, you do not need to draw any diagram for this question.
Answer:
| Characteristics | Renewable Energy Sources | Non-renewable Energy Sources |
| Definition | The resources that are continuously replenished and can never run out. | The resources that cannot be replenished or recycled and deplete over time. |
| Examples | Water Sunlight Wind Geothermal | Fossil fuels Coal Natural gas Petroleum |
| Environmental Implications | They are environment friendly as they are produced naturally, and do not emit any harmful gases or pollutants that can cause damage to the environment. | They are not environmentally friendly since some non-renewable energy resources emit carbon monoxide and carbon dioxide, thus causing pollution and ozone depletion respectively. |
| Maintenance Cost | They require less maintenance as compared to non-renewable energy sources. For example, Turbines in hydropower stations or in wind farms do not require any external system for their functioning or rotating their parts | They require more maintenance as a lot of time is consumed and takes considerable effort. For example, The process included in searching for coal mines like installation of complex machines, refining, drilling and transporting etc. is very time-consuming. |
| Efficiency | The efficiency of renewable sources and technology is low | The efficiency of non-renewable energy sources and technology is high |
(B) Give a brief account of Optic Fibers. What is their importance in the present-day telecom system?
Question Breakdown:
This question has basically two parts. In the first part, the examiner has asked you to describe optic fibre briefly in your own words. When done writing about Optical fibres, its basics structure, and their working mechanism; move towards the next part of the question which is their importance of them in the modern world telecom system. So, you need to write its importance in bullets and points. Remember, being creative is what will make your paper stand out from other aspirants. Lastly, draw a diagram of optic fibre as well.
Answer:
Optical Fibers:
Optical fibre is the technology that is associated with the transmission of information as light pulses over a long distance along a glass tube or plastic wire or fibre.
The basic structure of Optical Fibers:
Optical fibre consists of four layers
1. Core made up of glass
2. Cladding is a reflective layer made up of glass or plastic
3. Coating cover as a protective layer
4. Jacket to bundle all fibres in one cable.
Working of Optical Fiber:
In a fibre-optic system, a machine called a transmitter turns information into the light. Then the transmitter sends the light through optical fibres. As the light moves at a high speed through the core, it bounces off the cladding either by the phenomenon of total internal reflection or continuous refraction. If the fibre has a bend in it, the light can bounce off the cladding and turn the corner to follow the bend. At the end of the fibres, a machine called a receiver accepts the light. The receiver turns the light back into sound, pictures, or computer codes.
Importance of Optical Fibers in present-day telecommunication:
In present-day telecommunication, fibre optics is used widespread due to a number of reasons.
1. Much lower levels of signal attenuation
2. Fibre optics provides a much higher bandwidth allowing more data to be delivered.
3. They are much lighter than the coaxial cables that might otherwise be used.
4. Fibre optics does not suffer from stray interference pickup that occurs with coaxial cabling.
(C) What is the most dangerous part of a hurricane and how do cyclones affect humans?
Question Breakdown:
In the first part of this question, the examiner has asked you to explain the most dangerous part of the hurricane. However, before describing it, you need to write what actually the hurricane is in two to three lines. Then, while writing the most dangerous part, the better approach is to deal with it both structurally and functionally. In the next part of the question, you are supposed to write down the five impacts of cyclones that affect humans directly or indirectly. Remember, creativity and presentation is what make your paper standout among other aspirants
Answer:
Hurricanes:
A hurricane is a weather phenomenon that is essentially a rapidly rotating storm system with characteristics such as a low-pressure centre, strong winds, and thunderstorms that produce heavy rain.
The most dangerous part of a Hurricane:
- Structurally, the eye-wall of a cyclone surrounds the eye or base of the storm where the most damaging winds and intense rainfall is found.
- Cyclones are often accompanied by strong winds, torrential rains and storm surges among which storm surge is the most dangerous part of a hurricane. It is an abnormal rise of water generated by hurricanes, over and above the predicted astronomical tide.
Effects of cyclones on humans:
Storms, Cyclones, Hurricanes, Typhoons, etc. are the terms used for the same process; however, their names are based on where they happen- location. Following are the impacts of cyclones/hurricanes.
1– The rise in sea level:
Cyclones out at sea can also destroy ships and cause shipwrecks which can cause many deaths. Money can also be lost if the ship is carrying expensive cargo.
2- Damage to the human infrastructure:
The cyclone’s strong winds can rip the roof of a house or destroy it entirely. It can send flying debris into houses. Any objects that have not been tied down will get sent flying most likely never to be found again.
3- Migration of people:
After a cyclone has struck and the strong winds and flooding have subsided, people start to return to their houses to inspect the damage. Often the damage they find is devastating as almost everything is destroyed and thousands of people are left homeless.
4- Loss of biodiversity:
Cyclones leave negative impacts on biodiversity, causing the decline or disappearance of various varieties of plants and animal species.
5- Psychological impacts:
A disaster of any kind has long-lasting fear in minds of the masses. They have witnessed a large number of deaths, collapse of infrastructure, cries, pains and sorrow.
(D) What’s the difference between vaccines and antibiotics? How do antibiotics and vaccines contribute to health?
Question Breakdown:
In the first part of this question, the examiner has asked you to draw a comparison between vaccines and antibiotics. So, draw a table and write down all the possible differences between the two terms. When done, make another heading and move towards the next part of the question which is their importance of them in relation to our health system. Write down all the reasons about how they are important to maintain the body system fit and fine. Lastly, you do not need to draw any diagram for this question.
Answer:
| Differences | Vaccines | Antibiotics |
| Definition | Dead or inactivated organisms or compounds are used to provide immunity to a particular infection. | Small molecular compounds that are effective in treating animals and humans against certain diseases. |
| Source | They are produced by live or inactivated microbes, toxins, and antigens. | Antibiotics are prepared naturally or synthetically by different drugs. |
| Functions | They are used to build immunity and prevent viral infections. | However, antibiotics are used to treat bacterial and parasitic infections. |
| Adverse Effects | Sometimes cause allergic reactions and swelling. | They can cause gastric discomfort and allergic reaction. |
| Examples | Polio VaccineMeasles, Mumps and Rubella (MMR) Vaccine | PenicillinCephalosporin’s |
Contribution of vaccines and antibiotics toward health
Vaccines and antibiotics have significantly contributed to improving health and also increasing the longevity of human beings as Vaccines strengthen your immune system so infections can’t get started and antibiotics help fight an infection that is already making you sick.
Question – 04
(A) What is the importance of forests in the economy of a country?
Question Breakdown:
In this question, the examiner has simply asked you to write down the importance of forests in the economy of a country. Thus, all you have to do is write the important points of significance in bullet form. Remember, writing too much can never help you get maximum marks. Being creative is what will award you maximum marks in your GSA paper. Lastly, you do not need to draw any diagram for this question.
Answer:
Forests are the most valuable assets for every nation. They provide timber, firewood, forage, and medical plants. They help in the conservation of soil fertility and thus enhance its productivity. They also help sustain the country’s wildlife and provide a lot of recreational activities.
Significance of Forests in the Economic Development of a country:
1- Monetized and cashed value contributions from the forests:
The forest sector is also an important source of both formal and informal jobs, particularly in remote areas where there are few economic alternatives. A lot of people are engaged as woodcutters, sawyers, carters, and craftsmen, and therefore are full-time employed because of the presence of forests.
For example: In Pakistan, 500,000 workers are employed by forest-products industries such as furniture, village carpentry, matches, particleboard, boats, crates, boxes, paper, pulp, and chipboard.
2- Forests economy at the household and community level:
Wood grown in forests serves as a source of energy for rural households. Wood is used for furniture, infrastructure and interior of houses as a construction material, environment-friendly products, tools, weapons, and fuel.
3- Sustainability supply chains and forests:
Forest, being the storehouse for carbon, are solar-powered and renewable resources of energy and they also have the potential to mitigate climate change by replacing non-renewable material and can act as a substitute for fossil fuels. Hence, they work as a sustainable supply chain for any country.
4- Paper obtained from woods:
According to some reports, the degree of economic development of a country is determined by its per capita consumption of paper. Hence, whenever a country gets economically developed, paper is utilized as packaging material, in communications and in scores of other uses.
(B) Give a brief account of Biotechnology.
Question Breakdown:
In this question, the examiner has asked you to briefly explain Biotechnology in your words. Now, it is up to you how to explain it. You can either write definitions, examples, advantages, and disadvantages, or you can write define, discovery and importance. Writing types and importance separately can bulk your question; thus, it is better to merge the types and importance of biotechnology to effectively comprehend the answer. There is no need to draw any diagram; however, you can draw relevant keys.
Answer:
Biotechnology:
Biotechnology is the branch of science that makes the use of living organisms or their component molecules, cells, tissues, and organs through scientific or engineering procedures for the benefit of mankind.
Discovery:
The word ‘biotechnology’ was first coined by Hungarian engineer Karl Ereky in 1919 who used it to describe the natural processes to create industrial products.
Importance of Biotechnology:
Biotechnology has been a blessing for human life. Following are some of the major categories which are encompassed by biotechnology.
1- Medical Biotechnology (Red):
As the name indicates, medical biotechnology is majorly concerned with the field of human health and medicine.
✓ It aids in the formulation of pharmaceuticals by determining the dosage of patients and, more particularly, treating patients based on genetic code.
✓ In therapeutic medicine, the preparation of vaccines, the production of insulin for diabetes treatment and gene therapy for HIV/AIDS and cancer tissue treatment are all due to biotechnology.
2- Industrial Biotechnology (White):
The procedures deal with the organic technology advancement in the industry.
✓ It focuses on the use of natural resources for industrial processes that utilize less energy with high productivity.
✓ It improves the efficiency and competence of manufacturing while lowering the environmental impact. To conserve natural resources, waste goods can be handled and recycled.
3- Environmental Biotechnology (Green):
Environmental and agricultural biotechnology comes under the category of green biotechnology.
✓ Biotechnology can be used for energy production, bioremediation, and waste treatment to clean the surroundings.
✓ It improves crop productivity by providing protection against diseases, which is doubled or even tripled compared to a typical harvest.
✓ Biotechnology can transmit genetic traits of crops that can endure changing climate conditions while also improving nutritional quality.
4- Marine Biotechnology ( Blue):
Blue biotechnology deals with the research of marine life, particularly sea animals.
✓ This blue biotechnology has a significant impact on the industrial, environmental, and food sectors since submarines create vast quantities of protein, enzymes, biomaterials, and biopolymers.
(C) Do the mammals also lay eggs? If yes, where in the world do they live? Write the name of some of them.
Question Breakdown:
In this question, the examiner has asked a question about egg-laying members. In this case, start your answer with a direct statement before defining them. When done, move to the next part of the question in which examiner has asked you to write the habitat of those animals with examples. Remember, writing too much can never help you get maximum marks, only your relevancy and presentation will make your paper stand out.
Answer:
Egg-laying Mammals:
Not all the members lay eggs. However, there is a group of mammals-called Monotremes- for Kingdom Animalia that lay eggs instead of giving birth to their young ones.
The Habitat and Examples of Egg-laying Mammals:
1. The duck-billed platypus is native to Tasmania and the neighbouring areas of eastern Australia.
2. There are four species of Echidna distributed as follows:
✓ Short-Beaked found across Australia and into New Guinea.
✓ Eastern Long-Beaked lives in humid forests, especially above sea level, in New Guinea.
✓ Sir David’s Long-Beaked Echidna lives in the Cyclops Mountains of New Guinea.
✓ Western Long- Beaked Echidnas live in alpine meadows and Montane forests. They are considered critically endangered; however, those that are remaining live in New Guinea.
(D) How can the Sun have such a strong gravitational field if it’s made of gases?
Question Breakdown:
In this question, the examiner has asked you to explain the reason for the sun having a gravitational field. Therefore, you need to answer your question with the definition of the gravitational field, and the factors on which gravity depends. Then, link the formula for describing the answer to your question. Remember, stick to what the examiner has actually asked, and do not stretch your question with unnecessary information if not required. No diagram is needed in this question
Answer:
Gravitational Field:
Every body of matter in this universe attracts other bodies of matter toward itself with a force known as gravitational force.
Factor Affecting Gravitational Field:
Following are the factors that affect the gravitational field of an object.
✓ Mass
✓ Distance
F ∝ m/d2
Why sun has a very strong magnetic field?
Although the sun is made up of a huge amount of gasses, it does not matter if a substance is comprised of gas or a liquid or a solid. The only physical factor that depends is mass, and the sun is extremely massive than all the planets of the solar system; thus, the sun has way more gravitational field through which the sun attracts all planets towards it.
Question – 05
(A) What does Ozone depletion mean and how can we protect the ozone layer?
Question Breakdown:
In the first part of the question, the examiner has asked you to define the term ozone depletion in your own words. In the second part, the question demands the suggestions of protecting the ozone layer in three to four bullets. In the end, draw a diagram depicting ozone layer depletion.
Answer:
Ozone Depletion:
It is a process where atomic particles such as chlorine and bromine react with ozone molecules (O3) and can cause the ozone molecules to break down. The ozone layer present in the stratosphere functions in a way that it absorbs the UV rays and protects the earth from these rays emitted by Sun, however, depletion of the ozone layer means the earth will be exposed to ultra violate rays which can cause serious health issues such as cancer, blindness, and genetic mutation.
How Ozone can be protected?
Ozone layers can be protected by adopting various measures. The depletion of the ozone layer is a formidable challenge and various programmes have been launched by the government of various countries to prevent it. However, pragmatic steps should be taken at the individual, societal, national and, above all, global levels to prevent the depletion of the ozone layer.
Measure to protect the ozone layer:
- Discontinuing the products which produce Chlorofluorocarbons (CFCs) Hydro-chlorofluorocarbons (HCFCs) and Halogens:
CFCs (chlorofluorocarbons), HFCs, halogenated hydrocarbon, and nitrous oxide are some of the most dangerous gases as they have a very high global warming potential (GWP). Thus, discontinuance of all the products that are responsible for the release of these gases can protect the ozone layer from further depletion. - Reducing the use of Pesticides:
They contribute immensely to the ozone depletion process so there is a dire need to reduce their usage. It can be controlled by adopting natural methods to get rid of pests and weeds. - By minimising the use of Vehicles:
Switching or encouraging the public to switch from private transport to public can play role in reducing the emission of greenhouse gases, which is also a stimulant to ozone depletion.
(B) What are the different types of a network? Explain each briefly.
Question Breakdown:
The question demands you to write down different types of a network briefly. For this purpose, first, write what is a computer network. Then, explain the types of a network with definition, example, and diagram of each in detail. Since the examiner has not specified on which basis you need to explain the types, always go for the most accepted categorization; for instance, in this case, you are supposed to categorize the network on the basis of coverage area.
Answer:
Computer Network:
A network is a group of computers that are linked together in a way that enables the computer to communicate with another computer and share its resources, data, and applications.
Typed of a Network:
Based on the size of the coverage area, a network is mainly of four types
1- LAN (Local Area Network):
A computer network that covers only a small area, for example, offices, buildings, etc. A LAN encompasses two or more computers connected over a server. In LAN, the data transfer system is extremely fast and provides higher security.
For example:
The two important technologies involved in this network are Ethernet and Wi-fi.
Diagram:
2- PAN (Personal Area Network)
A network that is arranged within an individual personal area connecting the computer devices of personal- covering as far as 10 meters- use is known as Personal Area Network.
For example:
USB, computers, phones, tablets, printers, etc., are some examples of PAN.
Diagram:
3- MAN (Metropolitan Area Network)
A metropolitan network area is larger than a local area network but smaller than a wide area network, i.e., it connects computers over a geographical distance through a shared communication path over a city, town or metropolitan area.
For Example:
A series of wireless routers distributed across a city is an example of MAN.
Diagram:
4- WAN(Wide Area Network)
A computer network that connects computers over a large geographical distance through a shared communication path is called a wide area network. It is extended over many locations rather than limited to a limited location.
For Example:
The Internet is one of the most widespread examples of a Wide Area Network.
Diagram:
(C) Why an indiscriminate/casual use of Antibiotics may prove dangerous?
Question Breakdown:
In this question, the examiner has asked you to explain the dangers associated with over usage of antibiotics. Remember, before writing the answer to such a reasoning question, always define and exemplify the jargon in four to five lines before moving to the real question. Further, the reasons must be comprehensive yet to the point which proves your answer. Remember, writing too much can never help you obtain maximum marks, presentation is what makes your paper stand out among thousands
Answer:
Antibiotics:
An antibiotic is a type of antimicrobial substance that is used to treat bacterial and other microbial infections.
For Example:
✓ Penicillin
✓ Cephalosporin
✓ Tetracycline
✓ Aminoglycosides
Dangers associated with the casual use of Antibiotics:
Since antibiotics work on the basis of a particular mechanism on specific receptors, they are safe to use until taken according to a prescribed dose for a particular number of days. However, taking antibiotics repeatedly may lead to adverse effects on the body.
- Resistance to Infection:
The repeated intake of antibiotics without the actual use, such as for common cold and flu may develop resistance to the causative bacteria that adopt changes in their structure leading to the killing and prevention of organisms impossible when required. - Destruction of Natural Bacteria:
The inappropriate use of antibiotics sometimes also kills the naturally occurring good bacteria, which exposes the body to many other killing infections, for instance, fungal and yeast infections. - Adverse Reactions of Antibiotics:
Antibiotics also produce adverse effect on the body that make the natural defence system of the body weak and imposes deadly effects on the other organs including the kidneys, liver, and gastric system.
(D) Why do atoms form bonds? Name three major types of chemical bonds.
Question Breakdown:
In this question, the examiner has asked you to comprehensively explain the reason why atoms form bonds, but before that, don’t forget to write the definition of bonding in your own words. When done, move to the second part of the question that demands the types of chemical bonds. Thus, describe each time of the bond with proper definitions, examples, and diagrams. Remember, writing too much can never assure you the maximum marks; the presentation of your paper is what matters.
Answer:
Chemical Bonding:
The formation of a chemical bond between two or more atoms, molecules, or ions to give rise to a chemical compound is called Chemical Bonding.
Why do Atoms form Bonds?
Atoms form bonds because
- They always yearn to reach the most stable (lowest energy) state via donating, accepting, or sharing of electrons.
- Atoms are only satisfied when they fill their valence shell with electrons and satisfy the octet rule by having eight valence electrons.
Types of Bonds:
1- Covalent Bond:
A covalent bond is the force of attraction that holds together two nonmetal atoms that share a pair of electrons. One electron is provided by each atom, and the pair of electrons is attracted to the positive nuclei of both atoms.
For Example:
In the water molecule, hydrogen and oxygen form covalent bonds.
Diagram:
2- Ionic Bond:
An ionic bond is the force of attraction that holds together oppositely charged ions. Ionic bonds form crystals instead of molecules.
Example:
Sodium Chloride crystals
Diagram:
3-Metallic Bond:
A metallic bond is the force of attraction between a positive metal ion and the valence electrons that surround it—both its own valence electrons and those of other ions of the same metal. The ions and electrons form a lattice-like structure.
Example:
Copper
Diagram:
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Question – 06
(A) Moiz was trying to sleep at one night but there was too much noise around him. His clock ticked every 5 second: a tap was dipping every 7 seconds and a pet dog snored every 12 seconds. He noticed on his clock that all three things happened together on the stroke of midnight. Find after how many seconds all three things happened together again?
Solution:
Clock ticked = every 5 sec
Tap was dipping= every 7 second
Pet dog snored= every 12 second
Happened together= Midnight= 12 a.m.
After how many seconds do all three things happen together again =?
Prime Factorization method:
5 = 5
7 = 7
12=2x2x3
LCM= 2x2x3x5x7= 420
Thus, after 420 seconds all three things happened together again.
(B) One pipe can fill a pool 1.25 times as fast as a second pipe. When both pipes are opened they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?
Solution:
Let n= time taken by the faster pipe
1.25n = time taken by the slower pipe, and we know that:
Time taken by both pipes= 5
So, according to the given scenario:
5/n + 5/1.25n = 1
6.25 +5 = 1.25n
1.25n= 11.25 hours
n= 11.25-1.25
n= 9 hours
So the faster pipe takes 9 hours while the slower pipe will take 11.25 hours.
(C) The cost for hiring a car for 2 days in 2018 was Rs. 264 which was 20% more than in 2013. What was the cost of hiring a car for 2 days in 2013?
Solution:
Let the cost in 2013 = x
As given in 2018;
X + 20% (x) = 264
X + 20x/100 = 264
120x/100= 264
X = 26400/120
X = 220
Thus, in 2013, the cost of hiring a car for two days was Rs. 220.
(D) What do you understand by the measure of central tendency? State its types
Solution:
Central Tendency:
Central Tendency can be defined as the tool and techniques that are used to measure the central value of a given data. Its main function is basically to analyze and interpret data which sometimes can be so large in numbers that it’s not possible to calculate it that way. Thus, central tendency measures are used to interpret such types of data.
Types of central tendency:
There are mainly 3 types of central tendency i.e., Mean, Median, and Mode.
What is Mean?
The mean is defined as, the sum of the values divided by the number of values.
Mean = sum of all values/ total number of values
= 15+15+16+16+16+17+17+18+19/ 9
= 149/9
= 16. 556
What is Median?
The middle value of an arranged data set is called median. Here, arranged data means writing all the values in ascending order, and the position of median of a given data set can be calculated as:
Median= n+1/2
What is Mode?
The mode is the most repeated value in a data set.
Question – 07
(A) Classification of blood groups is based on the presence or absence of inherited antigenic substances on the surface of red blood cells. In a survey of British population the blood group distribution among 1000 people was as follows: 300 had blood group A, 325 had blood group B, 250 had O and 125 AB. Out of this group a person was selected at random, and calculate his probability of having blood group AB
Solution:
Given data:
total people tested = 1000
Blood group A= 300
Blood group B = 325
Blood group O = 250
Blood group AB = 125
Required:
Probability of Blood group AB=?
Solution:
Probability of Blood group AB = 125/1000 = 25/200 = 5/40 = 1/8
(B) A farmer keeps hens and rabbits on his farm. One day, he counted a total of 70 heads and 196 legs. How many more hens than rabbits does he have?
Solution:
Let H shows a hen
And R shows a rabbit
Total number of heads = 70
Total number of legs = 196
More hens than rabbits =?
As each hen and each rabbit has one head, according to the given statement, the equation of head would be
H + R = 70 (equation a)
As each hen has 2 legs and each rabbit has 4 legs, so according to the given statement, the equation of legs would be
2H + 4R = 196 (equation b)
Now, if we multiply equation a with 2 (Elimination method)
2(H + R) = 2(70)
2H + 2R = 140 (equation c)
Now, subtract equation c from equation b
2H + 4R = 196
2H + 2R = + 140
0 + 2R = 56
R= 56/2
R= 28
By Putting the value of R in the equation a
H + (28) = 70
H= 70 – 28
H= 42
So,
Hens = 42
Rabbits = 28
42-28= 14
Hence, there would be 14 more hens than rabbits.
(C) What is a polygon? Describe different types of a regular polygon.
Solution:
Polygon:
A polygon is a closed two-dimensional figure composed of straight-line segments that meet at their endpoints. The line segments of polygons are called sides, and each endpoint is called a vertex. Polygons have at least three sides and three angles, and their sides must be straight.
Types of Regular polygon:
Regular polygons are those polygons that have equal sides and angles. Some of the types of regular polygons include:
Triangle
✓ Having three equal sides
✓ Sum of internal angle=180 degrees
Square
✓ Having four equal sides
✓ Sum of internal angle=360 degrees
Pentagon:
✓ Having five equal sides
✓ Sum of internal angle= 540 degrees
Hexagon:
✓ Having six equal sides
✓ Sum of internal angle= 700 degrees
Heptagon:
✓ Having seven equal sides
✓ Sum of internal angle= 900 degrees
(D) In a certain code, COMPUTER is written as RFUVQNPC. How will MEDICINE be written in code language?
Solution:
There are 8 letters in the word COMPUTER as well as in RFUVQNPC
Here, the technique/pattern to obtain the coded word can be by taking the immediately following letters of the word, expect the first and the last letters of the given word but in the reverse order. It means, in the coded form , the first and the last letters have been interchanged while the remaining letters are coded by taking their immediate next letters in the reverse order i.e.,
So, the coded word for medicine would be written as:
EOJDJEFM
Question – 08
(A) Seven piano students- T, U, V, W, X, Y and Z-are given a recital and their instructor is deciding the order in which they will perform.
Each student will play exactly one piece, a piano solo. In deciding the order of performances, the instructor must observe the following restrictions:
(i) X cannot play first or second
W cannot play until X has played.
Neither T nor Y can play seventh.
Either Y or Z must play immediately after W plays.
V must play immediately after or immediately before U plays
(ii) If V plays first, which one of the following must be true
T plays sixth
X plays third
Z plays seventh
T plays immediately after Y
W plays immediately after X
Solution:
Seven piano students = T, U, V, W, X, Y, Z
By considering the given conditions, the following would be the possible order of students playing the piano
- First Possibility
| Order | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Students | V | U | X | W | Y | T | Z |
- Second possibility
| Order | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Students | V | U | T | X | W | Y | Z |
Therefore, by looking the above-mentioned possibilities, Z plays seventh must be true.
(B) U = {Whole number from 10 to 24}
A = {Even number}
B = {Number divisible by 5}
Write down the number of elements of A∩B
Solution:
According to the given data:
U = [Whole number from 10 to 24]
It means:
U = [10, 11, 12, 13, 14, 15, 16, 17 ,18 ,19 ,20 ,21 ,22 ,23 ,24 ]
A = [Even Number]
A = [10, 12, 14, 16, 18, 20, 22, 24]
B = [Number divisible by 5]
B = [10, 15, 20]
Number elements of A∩B =?
A∩B= [10, 12, 14, 16, 18, 20, 22, 24] [10, 15, 20]
= [10, 20]
Hence, the number of elements of A∩B is two i.e., 10 and 20.
(C) In the following diagram A represents American, S represent scientist and P represents politicians:
(i) American those are politicians but not scientists will be?
(ii) Scientists which are politicians but not Americans will be?
Solution:
Americans are represented by = A
Members of American = c, d, b, a
Politicians are represented by = P
Members of politicians = b, a, g, f
Scientists are represented by = S
Members of scientist = d, e, a, f
American who are politicians but not scientists will be
Considering the given diagram,
Hence, it is clear from the diagram that b is the Americans who are politicians but not scientists.
Scientists which are politicians but not Americans will be
Considering the given diagram,
Hence, it is cleared from the diagram that f is scientist who is politician but not American.
(D) Each packet of washing powder carries a token and 4 tokens can be exchanged for free packet. How many free packets will I receive if I buy 64 packets?
Solution:
The number of free packets= no of packet bought/ no of free tokens exchanged
64 packets = 64 tokens
Now,
64/4 = 16 Free Packets
Similarly,
16/4 = 4 More Free Packets
Also,
4/4 = 1 More Free Packet
Now, by adding all the free packets, we get
16 + 4 + 1 = 21 Free Packets
Hence, 21 free packets will be received if one buy 64 packets.
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