Role of Oxygen

Q.

What happens when you bring a burning splint near a test tube rich in oxygen?

1. The splint glows brightly.

2. The splint breaks off

3. It extinguishes.

4. Nothing happens

Q.

Do scuba divers need to carry oxygen cylinders with them.

1. Yes
2. No

Q. Nitrogen does not support combustion.

1. True
2. False

Q.

Why do body cells require oxygen?

Q.

Which component of air is necessary for humans to get energy from food?

1. Nitrogen

2. Oxygen

3. Water vapour

4. Carbon dioxide

Q.

Pick the odd one out. Give reason for the same. [1 MARK]
nitrogen, oxygen, carbon dioxide.

Q.

State true or false.
Scuba divers carry oxygen cylinders with them.

1. False

2. True

Q.

Air is present inside water.

1. True

2. False

Q. Plants in the presence of sunlight produce their food and release gas.

1. oxygen
2. carbon dioxide
3. nitrogen

Q.

Statement I: Mountaineers carry oxygen cylinders with them while climbing high mountains.

Statement II: The percentage of oxygen in air decrease with increasing altitude.

1. Statement I is true and statement II is the correct explanation

2. Both statements are false

3. Statement I is true and statement II is false

4. Statement I is false and statement II is true

Q.

It was rainy season and Karan was enjoying the rain in his garden just when he saw a snake moving towards him. He ran inside at full speed, brought a stick and killed the snake with it. He thinks that the snake was sent to kill him by one of his enemy. Do you think he is right?

Q.

84 Green plants need carbon dioxide gas to make food.

1. True
2. False

Q.

Nitrogen is slightly _________ than air.

Q.

Sam and John found it interesting to discuss about air. Sam further stated that air is one of the most important things that is required for the existence of life on earth as air is needed for respiration. John was not in agreement with Sam on this statement and argued that the organisms that are found in rivers, oceans and other water bodies do not have access to air but still they continue to live.

Which of the following can be an explanation for John's query?

1. Air is present in water in dissolved form.

2. Aquatic animals do not respire.

3. Aquatic animals do not require air for respiration.

4. Aquatic animals use water for respiration.

Q.

Deborah takes a candle and places it in a tub. She lights the candle and fills the tub with some water. Then she covers the candle with an inverted glass. What happens after some time?

1. Water rises in the inverted glass

2. Water level goes down in the inverted glass

3. The candle continues to burn

4. The water level remains the same

Q.

Which of the following contribute to the water vapour content in the atmosphere?

1. Respiration.

2. Transpiration.

3. Combustion.

4. Photosynthesis.

Q.

John was still not satisfied with the explanation given by Sam regarding organisms that live underwater for most or all of their life. So he asked Sam to demonstrate his explanation physically so that he can have a better understanding. John simply wanted to know about the source of air for the aquatic animals.

Sam decided to use an experiment to explain John so he performed the following experiment.

He took some water in a glass vessel. Heated it slowly on a tripod stand. Well before the water began to boil, he asked John to look carefully at the inner surface of the vessel. John observed that bubbles were coming up.

John asked 'where did these bubbles come from'?

Which of the following can be Sam's answer?

1. The bubbles come from dissolved air in water.
2. The liquid in the beaker is not water.
3. The bubbles are formed due to glass vessel.
4. The bubbles are water bubbles.

Q. supports the burning/fire.

1. Water
2. Oxygen
3. Nitrogen
4. Carbon dioxide

Q. Existence of which of the following is supported by Oxygen.

1. Human beings
2. Aquatic animals
3. Stones
4. Plants
5. Wood
6. Fire
7. Birds
8. Glass

Q. Carbon dioxide is necessary for plants. Why do we consider it as a pollutant? [2 Marks]

Q.

Kenneth explained about the most important component of air to John and Sam. John was satisfied with the answer but Sam wanted to add some more information to it. Sam further elaborated the properties of the most important component of air. He said, it is not only used by living organisms during respiration but it also supports_____________.

1. Distillation

2. Combustion

3. Evaporation

4. Condensation

Q.

Deborah takes a candle and places it in a tub. She lights the candle and fills the tub with some water. Then she covers the candle with an inverted glass. What happens after some time?

1. The water level remains the same

2. Water rises in the inverted glass

3. Water level goes down in the inverted glass

4. The candle continues to burn

Q.

Sometimes, when a person is caught with fire, a thick blanket is wrapped around him or her. This is done to

1. cut off the nitrogen supply.

2. keep the body cool.

3. cut off the inert gases supply.

4. cut off the oxygen supply.

Q.

Which gas is required for combustion?

1. Oxygen

2. Nitrogen

3. Carbon dioxide

4. Hydrogen

Q.

Which component of air is necessary for humans to get energy from food?

1. Nitrogen

2. Oxygen

3. Water vapour

4. Carbon dioxide

Q.

47Akshay went on an adventurous trip with his friends. He went climbing sky diving and underground water diving. He observed that while all the activities were pleasant during water diving, he and his friends felt nauseous and had breathing difficulties. He was aware of the same thing happening to his friends a few years back as he was mountain climbing.
(e) Have you observed any good values in Akshay?

Q.

77 Plants produce oxygen during the process of making their own food.

1. True
2. False

Q. ___ gas is evolved upon combustion of an organic substance along with water vapour