Questions

A 40% solution of Formaldehyde known as Formalin is used in the preservation of biological specimens because of its hardening action on proteins. 

Biodegradable substances can be broken down into simpler, harmless substances in nature with due course of time by the biological process such as action of microbes. They can be recycled as a part of food chain.

Here, Leather bags are biodegradable.

Words that sound the same but are spelled different are called homophones. Homophones are a type of homonyms.

Some of the Examples of homophones are ::

One - Won

Son - Sun

Hole - Whole

Loan - Lone

Steal - Steel

Which - Witch

What - Watt

Sea - See

A restrictive clause is one that limits the meaning of the word it describes.

For example :: 

The girl who lives next door is beautiful.

This restrictive clause limits "the girl" to say it's specifically the one next door.

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. 

Carbon dioxide is a main greenhouse gas, found in car exhaust pipes.
Methane and nitrous oxide is another type of greenhouse gas.

Oxygen is the only clean gas out there because we need it to survive. Therefore, the only gas that is not a greenhouse gas is Oxygen.

Arunachal Pradesh State has been declared as the Open Defecation Free state.