Quartz crystals normally used in quartz clocks etc. is chemically

Which of the gas is not known as green house gas?

Bromine is a

The hardest substance available on earth is

The variety of coal in which the deposit contains recognizable traces of the original plant material is

Tetraethyl lead is used as

Which of the following is used as a lubricant?

The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing, is

The gases used in different types of welding would include

The property of a substance to absorb moisture from the air on exposure is called