A. VERY SHORT ANSWER QUESTIONS: Answer in one-word
1. Which natural phenomenon shows the presence of wind around us?
Ans. Storm
2. Name the gas which turns lime water milky?
. Carbon Dioxide
3. Name the process in which oxygen of the air is consumed?
Ans Ans. Combustion
4. What is the kinetic energy of the moving air is called?
Ans. Wind energy
5. Which gas present in the atmosphere is used by plants during photosynthesis?
Ans. Carbon dioxide
B. SHORT-ANSWER QUESTIONS: Answer in 10-15 words
1. Does soil contains air? How is this air useful to certain organisms?
Ans. Yes, soil contains air. This air is useful to the organisms that live in the burrows and holes in deep soil for breathing.
2.What happens to the oxygen gas taken up by all living organisms?
Ans. The oxygen gas taken up by all living organisms is utilized in oxidation of food to release energy.
3. What does the formation of droplets on the outer surface of a beaker (as shown alongside) containing ice cubes indicate?
Ans. The formation of droplets on the outer surface of a beaker containing ice cubes indicates the presence of humidity in the air.
4. How is the respiration similar to combustion of fuels?
Ans. Respiration is similar to combustion of fuels as both the processes consume oxygen and release energy and carbon dioxide.
5. What is meant by the term humidity?
Ans. The content of water vapour in the air is termed as humidity or relative humidity.
C. LONG ANSWER TYPE QUESTIONS: Answer in 20-25 words
1. Which of the gases present in the air is (a) the most and (b) the least, soluble in water?
Ans. (a) The most soluble gas in water is carbon dioxide.
(b) The least soluble gas in water is nitrogen.
2. Name the process which produces oxygen as one of the products. Write the reaction that takes place during the process.
Ans. The name of the process is photosynthesis which produces oxygen as one of the products.
3. How do animals and plants living in water and soil get oxygen?
Ans.
(a) The animals and plants living in water get oxygen dissolved in water. The animals get oxygen through gills and plants through diffusion process.
(b) The animals living in soil, get oxygen from the air trapped in the soil.
4. Draw a flowsheet diagram showing the balance of oxygen in the air.
Ans.
5. What is wind energy? Mention its two advantages.
Ans. The kinetic energy of the moving air is called wind energy. Its two advantages are:
(1) It is used for generating electricity by using windmills.
(2) It is used for transporting people and materials by using sailboats.
D. TICK THE ODD-ONE OUT GIVING REASON
1. Air, Oxygen, Nitrogen dioxide, Water vapour
Ans. Nitrogen dioxide because it is not the composition of air and rest others are composition of air.
2. Respiration, Burning, Combustion, Photosynthesis
Ans. Photosynthesis because it is the process of producing oxygen and rest others are the process of consuming oxygen.
3. Oxygen, Carbon dioxide, Photosynthesis, Chlorophyll, Wind energy
Ans. Wind energy because rest others are related to photosynthesis.
4. Birds, Human beings, Mammalian animals, Fish
Ans. Fish because it breathes through gills and rest others breathe through lungs.
5. Wind energy, Biogas, Parachutes, Electricity generation
Ans. Biogas because rest others are advantages of wind energy.
E. DEFINE THE FOLLOWING TERMS
1. Carbon dioxide-oxygen balance: The volume of oxygen released during photosynthesis is equal to the volume of carbon dioxide taken up by the plants. Therefore, the proportion of oxygen in the atmosphere remains almost fixed.
2. Respiration: The process of producing energy from the food due to its reaction with oxygen is called respiration.
3. Photosynthesis: Photosynthesis is a process by which green plants make their own food (in the form of carbohydrate) with carbon dioxide and water in the presence of sunlight and chlorophyll.
4. Wind energy: The kinetic energy of the moving air (called wind) is called wind energy.
HOTS: HIGHER ORDER THINKING SKILLS
1.Why it is advisable to breathe from our nose and not from our mouth?
Ans. It is advisable to breathe from our nose and not from our mouth because air contains several microorganisms and dust and chemical particles which are filtered by hair and mucous present on the nasal cavity. The nose also adds moisture and warmth to inhaled air for smoother entry to the lungs.
2. Why it is not advised to advised to sleep under a tree during the night?
Ans. It is the myth only.
3. A boy maintains an aquarium. On a cold day he put a small heater inside the aquarium to make water in it slightly warm. After a few hours, he found all fish dead. What is the reason for it?
Ans. As we know the solubility of the gases decrease when temperature rises. So due to the heat in the aquarium by the heater the solubility of oxygen decreases and fish died.
4. Have you seen vapour trail produced by a high flying aeroplane? What can be a possible explanation for it?
Ans. The vapour trail is formed when water vapour produced by the combustion of fuel in aeroplane engine condenses upon smoke particles in the plane’s exhaust.
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