____________ is the percentage of nitrogen in air.

(a)

78%

(b)

21%

(c)

0.03%

(d)

1%

Gas exchange takes place in plants using __________

(a)

Stomata

(b)

Chlorophyll

(c)

Leaves

(d)

Flowers

Nitrogen is used in the food packaging industry because it ________________

(a)

provides colour to the food

(b)

provides oxygen to the food

(c)

adds proteins and minerals to the food

(d)

keeps the food fresh

__________ is the active component of air.

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Oxygen

The gas given out during photosynthesis is _________.

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Oxygen

__________ can be seen moving in a beam of sunlight in a dark room.

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Tiny dust particles

________ gas turns lime water milky.  

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Carbon-di-oxide

Inhaled air contains a large amount of carbon-di-oxide.

(a) True

(b) False

Planting trees help in decreasing global warming.

(a) True

(b) False

The composition of air is always exactly the same.

(a) True

(b) False

Whales come up to the water surface to breathe in oxygen.

(a) True

(b) False

The balance of oxygen in atmosphere is maintained through photosynthesis in animals and respiration in plants.

(a) True

(b) False

Moving Air

(1)

Photosynthesis

Layer in which we live

(2)

Wind

Stratosphere

(3)

Ozone layer

Oxygen

(4)

Troposphere

carbon-di-oxide

(5)

Combustion

Photosynthesis : _____ :: Respiration : Oxygen.

78% of air : Does not support combustion :: _____ : Supports combustion.

What is atmosphere? Name the five layers of atmosphere

How do the roots of land plants get oxygen for breathing?

What will happen if you breathe through mouth?

Why do traffic assistants wear a mask on duty?

How do plants and animals maintain the balance of oxygen and carbon-dioxide in air?

Why is atmosphere essential for life on earth?