Explanation

CNG as compared to other fuels, causes less pollution.

The reason is that it is made up of methane.

There is less carbon emission.

Explanation

Explanation

Trees release carbon dioxide at night and carbon dioxide being heavier than air descendes.So a person sleeping under a tree breathes carbon dioxide which is harmful for the human body.

Explanation

Hydrogen and helium, the lightest two gases,

Hydrogen is a chemical element

It is colorless, odorless, tasteless, non-toxic, and highly combustible. 

Symbol: H

Atomic mass: 1.00784 u

Atomic number: 1

Atomic mass : zero

Boiling point: -252.9 °C

Discoverer: Henry Cavendish

Explanation

Carbon dioxide gas gives the beverage its sparkle and tangy taste and prevents spoilage.