Which of the following statements about $H_2SO_4$ is incorrect?

Hydrogen combines with other elements by

The vapor pressure of $......$ is maximum.

Which of the following is obtained when dihydrogen reacts with the alkali metals at high temperature?

Which of the following is commonly used in a laboratory desiccator?

The basic principle of the hydrogen economy is the transportation and storage of energy in the form of liquid or gaseous hydrogen. Which property of hydrogen may be useful for this purpose? Support your answer with a chemical equation if required.