Select the option that can be used as a one-word

The Bhopal tragedy was caused by the gas

Of the following which one pollutes the air of abig city? 

Chemical name of bleaching powder is

“Firefighting clothes” are made from

The gas that usually causes explosions in coal mines is

The element used for making solar cells is

When water itself combines chemically with some element or mineral it is called 

Mercury is a :

Which one of the following is known as the brown coal?

The total energy of revolving electron in an atom