Gas exchange takes place in plants using __________

The constituent of air that supports combustion is _________________

Nitrogen is used in the food packaging industry because it ________________

__________ is the active component of air.

__________ gas is given to the patients having breathing problems.

________ gas turns lime water milky.  

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

The composition of air is always exactly the same.

What will happen if we remove plants from the aquarium?

What should be done if the clothes of a person catch fire accidentally? Why?

What will happen if you breathe through mouth?

Biscuits kept open on a plate during monsoon days lose its’ crispness. Why?

Why do traffic assistants wear a mask on duty?

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

Can you guess why fire extinguishers throw a stream of carbon-di-oxide while putting - off fire?