1. Which gas is used in making the blue print of maps?
i. co2
ii. NH3
iii. H₂
iv. N2
Ans: iv. N2
2. What are the necessary required conditions to manufacture ammonia by Haber’s process?
i. heat, pressure and catalyst
ii. heat, pressure and promoter
iii. pressure, catalyst and promoter
iv. heat, pressure, catalyst and promoter
Ans: i. heat, pressure and catalyst
3. Which one is the lightest gas?
i. NH3
ii.co2
iii. O2
iv. H2
Ans: iv. H2
4. Which is the salt formed by the reaction between carbon dioxide and lime water ?
i. calcium bisulphate
ii. calcium bicarbonate
iii. calcium sulphate
iv. calcium carbide
Ans: ii. calcium bicarbonate
5. What proportion of ammonium chloride and calcium hydroxide is taken while preparing ammonia gas in the laboratory?
i. 3:1
ii. 2:3
iii. 2:1
iv. 1:2
Ans: iii. 2:1
6. What is the molecular formula of urea?
i. NH2CONH2
ii.CH3OCH3
iii. NH2 CONH4
IV. NH4 CONH4
Ans: i. NH2CONH2
7. The aqueous solution of gas that turns red litmus paper to blue is..
i. co2
ii. NH3
iii. H₂
iv. N2
Ans: ii. NH3
8. What percentage of nitrogen gas is found in the atmosphere?
i. 21%
ii. 0.03%
iii. 78%
iv. 87%
Ans:iii. 78%
9.Which of the following is NOT a greenhouse gas?
i. carbon dioxide
ii. sulphur dioxide
iii. Methane
iv. Nitrogen
Ans: iv. Nitrogen
10. Which of the following chemical compound is formed when carbon dioxide gas passes to lime water for a long time?
i. calcium sulphate
ii. calcium carbonate
iii. calcium bicarbonate
iv. calcium oxide
Ans: iii. calcium bicarbonate
11. What are the uses of carbon dioxide?
Ans: The uses of carbon dioxide are:
1. Fire Extinguishers
2. Food Preservation
3. Medical Applications
4. Welding and Metal Fabrication
5. Carbonated Drinks
12. Write any four physical properties of carbon dioxide.
Ans: Any four physical properties of carbon dioxide are:
1. Gas at Room Temperature
2. Colorless and Odorless
3. Heavier than Air
4. Solubility in Water
13. Give the formulae and the chemical names of slaked lime, limestone and urea.
Ans: The formulae and the chemical names of slaked lime, limestone and urea are:
1. Slaked Lime:
Chemical Formula: Ca(OH)₂
Chemical Name: Calcium Hydroxide
2. Limestone:
Chemical Formula: CaCO₃
Chemical Name: Calcium Carbonate
3. Urea:
Chemical Formula: CO(NH₂)₂
Chemical Name: Urea
15. How will you show that carbon dioxide is heavier than air?
Ans: Demonstrating Carbon Dioxide is Heavier than Air:
1. Materials Needed:
A candle
A small dish or saucer
Baking soda
Vinegar
2. Procedure:
i. Place a small dish or saucer on a table.
ii. Light a candle and place it at the center of the dish
iii. Add a small amount of baking soda to the dish.
iv. Slowly pour vinegar into the dish with baking soda. This will create carbon dioxide gas.
v. Observe what happens to the flame of the candle.
3. Observation:
The candle flame will start to flicker or go out when carbon dioxide gas is released from the vinegar and baking soda mixture. The carbon dioxide being heavier than air will sink and displace the air, affecting the flame.
This simple experiment shows that carbon dioxide, being denser or heavier than air, can displace air and affect the flame of a candle.
15. What is meant by dry ice? What is it used for?
Ans: Dry ice is solid carbon dioxide (CO2) in a frozen state. It’s called “dry ice” because it’s extremely cold and doesn’t melt into a liquid like regular ice.
Uses of Dry Ice:
1. Preserving Food
2. Preserving Food
3. Creating Fog or Smoke
4. Cleaning
16. How do you test whether a gas is carbon dioxide or not?
Ans: Testing for Carbon Dioxide
1. Materials Needed
i. Limewater (a clear, colorless solution of calcium hydroxide)
ii. A source of the gas suspected to be carbon dioxide.
2. Procedure:
a. Take a small amount of limewater in a clear container or test tube.
b. Carefully introduce the gas you want to test into the limewater. You can do this by gently blowing the gas into the limewater or using a pipette.
c. Observe what happens to the limewater.
3. Observation:
If the gas is carbon dioxide, the limewater will turn cloudy or milky. This happens because carbon dioxide reacts with calcium hydroxide in the limewater to form calcium carbonate, which is insoluble and creates the milky appearance.
17. What happens when carbon dioxide is passed into lime water for a short time?
Ans: When carbon dioxide is passed into lime water for a short time, the lime water, which is a clear and colorless solution of calcium hydroxide, turns milky or cloudy.
19. What is meant by photosynthesis? Give the chemical reaction involved in it.
Ans: Photosynthesis is the process through which plants, algae, and some bacteria use energy from sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen.
Chemical Reaction:
The overall chemical reaction for photosynthesis is:
6 CO2+6 H2O+light energy→C6H12O6+6 O2
In simpler terms, during photosynthesis, six molecules of carbon dioxide (CO2) and six molecules of water (H2O) combine with light energy to produce one molecule of glucose (C6H12O6) and six molecules of oxygen (O2). This process is essential for plant growth and provides oxygen, which is vital for life on Earth.
20. How is carbon dioxide collected in a laboratory?
Ans: Collection of Carbon Dioxide in a Laboratory:
Materials Needed:
A source of carbon dioxide (e.g., vinegar and baking soda reaction, dry ice, or a chemical reaction that produces CO2)
A gas collection apparatus (e.g., gas jar, gas syringe, or test tube)
Procedure:
a. Choose a suitable source of carbon dioxide. For example, you can mix vinegar and baking soda to produce carbon dioxide.
b. Place the source of carbon dioxide in a container or reactant vessel.
c. Connect the container to the gas collection apparatus.
d. Allow the reaction to occur, ensuring that carbon dioxide gas is produced and collected in the apparatus.
e. Close the apparatus to trap the collected carbon dioxide.
Observation:
Carbon dioxide gas will displace the air inside the apparatus and collect in the gas collection vessel. You can observe the gas and its properties.
21. What happens to moist blue litmus paper when it is dipped into carbon dioxide? Give reason.
Ans: When moist blue litmus paper is dipped into carbon dioxide, it turns red. This happens because carbon dioxide dissolves in water to form a weak acid called carbonic acid, which turns blue litmus paper slightly acidic, causing it to change color to red.
23. Write the chemical equation involved in the laboratory preparation of ammonia.
Ans: Here’s a simple explanation of the chemical equation involved in the laboratory preparation of ammonia:
Chemical Equation:
Ammonia (NH3) is prepared in the laboratory by reacting ammonium chloride (NH4Cl) with a strong base like sodium hydroxide (NaOH). The chemical equation for this reaction is:
NH4Cl+NaOH→NH3+NaCl+H2O
In simpler terms, ammonium chloride reacts with sodium hydroxide to produce ammonia, sodium chloride (table salt), and water. This is one way to prepare ammonia in the laboratory.
24. What are the necessary conditions for the manufacture of ammonia by Haber’s process? Give the balanced equation as well.
Ans: Necessary Conditions for Haber’s Process:
High Pressure: The reaction requires high pressure, typically around 200-400 atmospheres, to achieve a higher yield of ammonia.
Moderate Temperature: The process operates at a moderate temperature, usually around 400-450 degrees Celsius, to balance achieving a reasonable rate of reaction with minimizing energy costs.
Iron Catalyst: The reaction uses an iron catalyst to increase the rate of reaction and enhance the formation of ammonia.
Raw Materials: The essential raw materials are nitrogen gas (N2) obtained from the air and hydrogen gas (H2) usually obtained from natural gas.
Balanced Chemical Equation: The balanced chemical equation for the synthesis of ammonia in the Haber’s process is:
N2+3H2⇌2NH3
In simpler terms, nitrogen gas reacts with hydrogen gas to produce ammonia. This reaction is the basis of ammonia production in the Haber’s process.
25. What are the physical properties of ammonia?
Ans: The physical properties of ammonia are:
1. Ammonia is a gas at room temperature and pressure.
2. Ammonia is colorless, which means it does not have any distinct color.
3. Ammonia is highly soluble in water, forming a clear, colorless liquid solution known as aqueous ammonia.
4. Ammonia gas is lighter than air. It has a lower density than air, which means it rises in the atmosphere.
5. It has a strong, pungent odor that is easily noticeable.
26. Ammonia turns red litmus into blue. What does it show?
Ans: When ammonia comes in contact with red litmus paper, it turns the red litmus paper blue. This indicates that ammonia is a basic or alkaline substance, with a pH greater than 7 on the pH scale.
27. How can you prepare ammonium sulphate from ammonia?
Ans: Here’s a step-by-step explanation in bullet points:
1. Start with Ammonia:
Begin with a gas called ammonia, which is commonly used in cleaning products and fertilizers.
2. Mix with Sulfuric Acid:
Combine the ammonia with an acid, like sulfuric acid.
3. Chemical Reaction:
When you mix the ammonia and sulfuric acid, a chemical reaction occurs.
4. Formation of Ammonium Sulfate:
This reaction results in the creation of a new substance called ammonium sulfate.
5. Remove Excess Water:
If there is extra water in the mixture, you may need to remove it to obtain a solid form of ammonium sulfate.
6. Final Product:
The solid ammonium sulfate obtained can be used in various applications, including aiding plant growth in agriculture.
28. What type of litmus can help to confirm that a gas jar is filled with ammonia?
Ans: To check if a gas jar contains ammonia, you can use a special paper called “ammonia-sensitive litmus paper.” This paper is designed to change color in the presence of ammonia gas. If you place this paper near the opening of the gas jar and it changes color, then it confirms the presence of ammonia. The color change indicates that the gas in the jar is ammonia.
30. What is meant by liquor ammonia? Write any four uses of ammonia.
Ans: “Liquor ammonia” refers to a solution of ammonia gas in water, forming ammonium hydroxide. It is a household cleaner commonly known as “ammonia solution” or “ammonia water.”
Four uses of ammonia:
1. Ammonia helps clean things at home, like floors and windows, by removing dirt and stains.
2. Ammonia helps plants grow and become healthy when used in fertilizers.
3. Ammonia cools down things, like refrigerators and air conditioners, making them work well.
4. Ammonia is used to make lots of things we use, like chemicals, medicines, and materials for everyday items.
31. How does the atmosphere act as a blanket?
Ans: The atmosphere acts like a blanket for the Earth by trapping the Sun’s heat and keeping our planet warm. It allows sunlight in but prevents some of the heat from escaping, just like a blanket keeps you warm by trapping your body heat. This trapped heat regulates the Earth’s temperature, making it suitable for life.
32. Introduce greenhouse effect in your own words.
Ans: The greenhouse effect is like a natural cozy blanket for our planet. The Earth’s atmosphere, made of special gases, acts like this blanket, allowing sunlight in and trapping the Earth’s warmth. However, when we add too many of these special gases, like from burning fossil fuels, the blanket becomes too thick. A thicker blanket traps more heat, causing the Earth to get too warm, leading to climate issues like extreme weather and rising sea levels. It’s crucial to maintain the right balance in our atmospheric blanket to keep the planet comfortable and habitable.
33. Prepare a brief speech on global warming.
Ans: Today, I want to talk about a crucial issue that affects us all – global warming. It’s like our Earth having a fever. You know, when we get a fever, our body gets too warm, and we don’t feel good. The Earth is feeling the same way.
This happens because of something called the “greenhouse effect.” It’s like a blanket around the Earth that’s getting thicker and trapping too much heat. The Sun sends us warmth, and usually, some of it goes back to space. But now, with this thick blanket, a lot of that heat is staying here, making the planet warmer.
Why is this a big problem? Well, think about it. When you’re too hot, you feel uncomfortable, right? Our Earth is getting uncomfortable too. It’s causing more storms, floods, and even making the ice at the North and South Poles melt, which raises sea levels and can flood our homes.
The good news is, we can help. Just like when we’re too hot, we take off some layers, we can take off some “layers” of these heat-trapping gases. We can use less energy, be mindful of what we use, and maybe use more natural and clean ways to get our energy.
34. Describe the threat to the beauty of the historical monuments of Nepal due to acid rain.
Ans: Acid rain poses a serious threat to Nepal’s historical monuments. Pollutants in the air mix with rain, forming a corrosive acid that eats away at the delicate surfaces of ancient structures. This erosion weakens and cracks the stones and carvings, diminishing the beauty and historical value of these treasures. Preventing pollution is essential to protect these invaluable sites and preserve Nepal’s rich history.
35. Why does acidic soil affect the growth of trees and decrease the productivity of crops?
Ans: Acidic soil is like an unfriendly environment for plants. It affects tree growth and reduces crop productivity because most plants prefer a balanced and slightly acidic to neutral soil. Here’s how:
1. Acidic soil locks up vital nutrients plants need for growth, hindering their development.
2. Acidic soil can harm plant roots, making it harder for them to absorb water and nutrients.
3. Acidic soil increases aluminum levels, which can become toxic to plants, further impeding their growth.
4. The acidity disrupts beneficial soil microbes, affecting nutrient availability for plants.
Overall, acidic soil disrupts nutrient absorption, harms roots, introduces toxicity, and affects soil microbes, all contributing to stunted growth in trees and reduced crop productivity. Balancing soil pH is crucial for plant health.
36. Explain why acid rain is more likely to occur over thickly populated cities with many industries around them.
Ans: Acid rain is like a problem that often hovers over busy cities with lots of factories and people. Let me explain why this happens:
1. In cities with many industries and vehicles, there is a lot of pollution in the air. These pollutants, like sulfur dioxide and nitrogen oxides, mix with the clouds and moisture in the air.
2. When these pollutants mix with clouds, they create acid rain. It’s like mixing two things to make something new – in this case, pollutants and clouds make acid rain.
3. Cities with many industries produce a lot of these pollutants. The more factories and industries there are, the more pollutants released into the air. More pollutants mean a higher chance of acid rain forming.
4. Cities have lots of people and activities, which means more cars, buses, and trains that release these pollutants. People using things like fossil fuels (coal, oil) for heating homes or powering industries also add to the pollution.
So, when you have a mix of lots of industries, transportation, and a high population in a city, you get more pollutants in the air. When these pollutants mix with clouds, they create acid rain, making it more likely to happen over densely populated cities with numerous industries.
37. Write any two advantages of greenhouse effect in the atmosphere and two disadvantages of over greenhouse effect.
Ans: Any two advantages of greenhouse effect in the atmosphere and two disadvantages of over greenhouse effect are:
Advantages:
1. The greenhouse effect keeps the Earth warm enough for life to thrive by trapping heat from the Sun.
2. It helps balance the climate by regulating temperatures and creating conditions suitable for ecosystems.
Disadvantages:
1. Excessive greenhouse effect, caused by human activities, leads to global warming, resulting in extreme weather and ecological threats.
2. Overactivity of the greenhouse effect disrupts natural climate patterns and harms ecosystems, impacting plant and animal life.
38. What would happen if greenhouse gases were not present in the atmosphere of the earth?
Ans: Here are some point to explain it:
Extreme Cold:
Without greenhouse gases, heat from the Sun would escape, making Earth bitterly cold.
Frozen World:
Most water would freeze, turning our planet into an icy, uninhabitable place.
Struggle for Life:
Life, including plants and animals, would find it difficult to survive in such harsh, cold conditions.
Limited Growth:
Plants would struggle to grow without enough warmth, disrupting the food chain and impacting all living beings.
39. Suggest any two control measures of greenhouse and acid rain each.
Ans: Control Measures for Greenhouse Effect:
Reducing Emissions:
Use cleaner energy sources and improve energy efficiency to lower carbon dioxide and greenhouse gas emissions.
Planting Trees:
Increase afforestation and reforestation to absorb carbon dioxide and reduce overall greenhouse gas levels.
Control Measures for Acid Rain:
Industrial Emission Control:
Install scrubbers and catalytic converters in industries to reduce sulfur dioxide and nitrogen oxide emissions, major contributors to acid rain.
Cleaner Transportation:
Promote electric vehicles, fuel efficiency, and public transportation to decrease nitrogen oxide emissions from vehicles and combat acid rain.
40. Write two examples to show the formation of acid rain in the atmosphere of the earth.
Ans: Here are two original examples illustrating the formation of acid rain:
From Industries:
Factories release gases like sulfur dioxide and nitrogen oxides into the air when burning fossil fuels. These gases mix with moisture and form sulfuric acid and nitric acid, causing acid rain when it rains.
From Vehicles:
Vehicles burn fuels and release nitrogen oxides and sulfur dioxide. These combine with atmospheric moisture to create nitric acid and sulfuric acid, resulting in acid rain when it rains.
41. Write any four adverse effects of acid rain.
Ans: Any four adverse effects of acid rain are:
1. Damage to Buildings and Structures
2. Acid rain affects rivers, lakes, and streams, making the water more acidic. This acidity can harm aquatic life, particularly fish and other organisms
3. Acid rain damages soil quality and fertility by altering its pH levels.
4. Acid rain damages and weakens plants by leaching important nutrients from the soil and interfering with their ability to absorb nutrients.
43. If a worker is going to enter into a well for cleaning purpose what suggestions will you give to him to pretest that the well is safe to enter or not?
Ans: The suggestions that i will pretest are given below :
1. Use a gas detector to check for harmful gases. Do not enter if unsafe and ensure proper ventilation.
2. Test oxygen levels; it should be at least 19.5% for safe entry. If low, ventilate the well.
3. Inspect the well’s structure for stability. Do not enter if it seems unstable.
4. Wear appropriate safety gear, including a harness, hard hat, gloves, and safety boots.
5. Ensure proper training, have someone monitor from above, and be ready with a lifeline for communication and rescue.
6. Have a clear emergency plan, including communication methods and contact numbers, in case of an accident.
7. Use proper, explosion-proof lighting for clear vision and safe work.
8. Verify necessary permits and compliance with local safety standards before entering.
44. Ammonia cannot be collected in a gas jar by the downward displacement of water and air.
Ans: Ammonia is lighter than air and doesn’t dissolve well in water. So, using the downward displacement method with water won’t effectively collect ammonia in a gas jar.
45. A moist red litmus paper is used to test ammonia gas.
Ans: A moist red litmus paper is utilized to test ammonia gas. When exposed to ammonia, the red litmus paper turns blue. This color change confirms the presence of ammonia, making it a handy tool for detecting the gas.
46. Lime tower (CaO) is used for preparation of ammonia.
Ans: A lime tower, using calcium oxide (CaO), is employed in the preparation of ammonia. The CaO in the lime tower helps remove impurities and moisture from the air, creating favorable conditions for the ammonia synthesis process. It ensures a clean and dry environment, essential for efficient ammonia production.
47. Carbon dioxide is used in a fire extinguisher.
Ans: Carbon dioxide is like a helper in a fire extinguisher. When there’s a fire, it pushes away the air around the fire. Since fire needs air to stay alive, when we use carbon dioxide, it takes away the air and the fire goes out. It’s a helpful way to stop fires from spreading.
48. H2SO4 is not used in the preparation of CO₂.
Ans: Sulfuric acid (H2SO4) is not used in making carbon dioxide (CO2). Instead, carbon dioxide is typically produced from sources like burning fossil fuels or through chemical reactions that involve substances containing carbon, such as limestone (calcium carbonate). Sulfuric acid isn’t a part of this process.
49. The mouth of hard glass test tube is slanted down during laboratory preparation of ammonia gas.
Ans: The top of a hard glass test tube is tilted downward when preparing ammonia gas in a laboratory. This slanted position helps in directing the gas flow and preventing any moisture or impurities from entering the apparatus. It allows for better collection and more accurate experimentation during the ammonia gas preparation process.
50. Carbon dioxide does not support burning but Mg burns in it.
Ans: Carbon dioxide doesn’t help things burn, but magnesium can still burn in it. When something burns, it usually needs oxygen, which is not available in carbon dioxide. However, magnesium is quite special; it has its own oxygen inside, so it can burn and create a bright light even in carbon dioxide.
51. It may be dangerous to clean a well.
Ans: Cleaning a well can be risky. There might be hidden dangers like harmful gases, unstable walls, or poisonous substances in the water. It’s important to take safety precautions and maybe even get help from experts to make sure it’s cleaned safely.
52. A moist blue litmus paper is used to test carbon dioxide gas.
Ans: A wet blue litmus paper is used to check for carbon dioxide gas. When carbon dioxide is present, the blue litmus paper turns red. This color change helps us confirm if carbon dioxide is around, making it a useful way to detect the gas.
53. Global warming is a global environmental issue.
Ans: Global warming is a big problem that affects the entire world. It happens when the Earth’s temperature goes up because gases like carbon dioxide trap heat from the sun in the atmosphere. This warming causes various issues like extreme weather, melting ice, and problems for plants and animals. I
54. Fossil fuels are the main sources of greenhouse gases.
Ans: Fossil fuels, like coal, oil, and gas, are the main sources of greenhouse gases because when we burn them for energy, they release gases like carbon dioxide, methane, and nitrous oxide. These gases act like a blanket, trapping heat in the atmosphere and causing global warming.
56. Carbon dioxide gas is collected in an open gas jar.
Ans: Carbon dioxide, being heavier than air, naturally sinks into an open gas jar when it’s produced. We can then cover the jar to collect and use the carbon dioxide.
