Black heart of potato is due

The SI unit of surface tension is:

Which one of the following gases is supporter of combustion?

Which of the following types of coal is called a brown coal among the following?

_______ is a simple device that is used to either break an electric circuit or complete it.

A gas is compressed at constant temperature. Which of the following will decrease?

Which gas is used in the process of photosynthesis?

The sky appears blue because of –

The blood sugar of an insect is:

What defines an ion?

The refractive index of glass is 1.5. What is the speed of light in glass? Speed of light in vacuum is 3.0 x 10⁸ m/s.