Identify the catalyst used in the reaction: $CO_2 + 2H_2 \xrightarrow{?} CH_3OH$

How many of the following statements is/are correct?
$(a)$ Mercury is the only metal that exists as liquid at room temperature.
$(b)$ Among non-metals,carbon has the highest melting point.
$(c)$ Hydrogen is the most abundant element in the universe.
$(d)$ Oxygen is the most abundant element in the earth's crust.

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.

Identify the hydride which is not correctly matched with the example given in brackets?

Which one of the following methods is used to prepare carbon monoxide on a commercial scale?

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?