Nitrogen is needed by the plants to make

1

(a)

fats

(b)

carbohydrates

(c)

proteins

(d)

minerals

About one fifth of ordinary air is

1

(a)

nitrogen

(b)

carbon dioxide

(c)

water vapour

(d)

oxygen

Usha took a lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles cointain 

1

(a)

water vapour

(b)

only oxygen gas

(c)

air

(d)

None of these

The components of air which are harmful to living beings are _______

1

(a)

nitrogen and carbon dioxide

(b)

dust and water vapour

(c)

dust and smoke

(d)

smoke and water vapour

Which of the following components of air is present in the largest amount in the atmosphere?

1

(a)

Nitrogen

(b)

Oxygen

(c)

Water vapour

(d)

Carbon dioxide

Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations:
(i) Bubbles of air came out from the bottle.
(ii) Some water entered into the bottle.
(iii) Nitrogen gas came out in the form of bubbles and oxygen gas dissolved in water
(iv) No bubbles formed, only water entered into the bottle 
which observation(s) is/are correct? 

1

(a)

(i) and (ii)

(b)

Only (iv)

(c)

(iii) and (iv)

(d)

Only (i)

Mountaineers carry oxygen cylinders with them because

1

(a)

there is no oxygen on high mountains

(b)

there is deficiency of oxygen on mountains at higher altitude

(c)

oxygen is used for cooking

(d)

oxygen keeps them warm at low temperature

What is not true about air?

1

(a)

It makes the windmill rotate

(b)

It helps in the movement of aeroplanes

(c)

Birds can fly due to presence of air

(d)

It has no role in water cycle

Wind does not help in the movement of which of the following?

1

(a)

Firki

(b)

Weather cock

(c)

ceiling fan

(d)

Sailing yacht

Which of the following statements is incorrect?

1

(a)

All living things require air to breathe

(b)

We can feel air but we cannot see it

(c)

Moving air makes it possible to fly a kite

(d)

Air is present everywhere but not in soil

The presence of which component in air varies from place to place?

1

(a)

Oxygen

(b)

Nitrogen

(c)

Water vapour

(d)

Carbon dioxide

Which of these is not true for combustion?

1

(a)

Oxygen is formed

(b)

CO₂ is formed

(c)

Oxygen is used up

(d)

Nitrogen does not change

Which of these is not an organ for taking in oxygen?

1

(a)

Lungs 

(b)

Gills

(c)

Stomata

(d)

Atmosphere

Which of the following gases protects us from ultraviolet rays?

1

(a)

Oxygen

(b)

Ozone

(c)

Carbon dioxide

(d)

Nitrogen

The amount of water vapour in the air at any place and time is:

1

(a)

Atmosphere

(b)

Humidity

(c)

Fog

(d)

Smoke

CNG means:

1

(a)

Common Natural Gas

(b)

Compressed Natural Gas

(c)

Common Natural Gasoline

(d)

Compressed Natural Gasoline

Oxygen and carbon dioxide are replaced in nature through:

1

(a)

Photosynthesis

(b)

Respiration

(c)

Both (a) and (b)

(d)

None of these

Air is a type of:

1

(a)

Mixture

(b)

Compound

(c)

Gas

(d)

Element

The rate of photosynthesis is very high during:

1

(a)

evening

(b)

day time

(c)

night

(d)

midnight

Earthworm takes oxygen from the soil through:

1

(a)

Lungs 

(b)

Gills

(c)

Moist skin

(d)

Spiracles

Which gas in the atmosphere is essential for respiration

1

(a)

Carbon dioxide

(b)

Oxygen

(c)

Argon

(d)

Nitrogen

Air is a mixture of

1

(a)

Oxygen and nitrogen

(b)

Carbon dioxide and oxygen

(c)

Various gases, dust particles and water vapour

(d)

Oxygen and dust particles

During photosynthesis, plants take in 

1

(a)

Carbon dioxide

(b)

Oxygen and nitrogen

(c)

Oxygen and dust particles

(d)

Only oxygen

Fish derive oxygen from:

1

(a)

the soil below water.

(b)

the dissolved air in water.

(c)

the atmospheric air.

(d)

none of these

The layer of air which surrounds the earth is:

1

(a)

atmosphere

(b)

air envelope

(c)

matter

(d)

none of these