Which of the following is a poor conductor of electricity?

The charring of sugar takes place when treated with concentrated $H_2SO_4$. What is the type of reaction involved in it?

Which property among the following is the same for both hydrogen and deuterium molecules?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Physical properties of isotopes of hydrogen are different.
Reason $R$: Mass difference between isotopes of hydrogen is very large.
In the light of the above statements,choose the correct answer from the options given below:

$NaH$ is an example of:

Which of the following drying agents reacts with $CO_2$ and also removes moisture?