If the boiling point of $H_{2}O$ is $373\,K$,the boiling point of $H_{2}S$ will be:

Which of the following statements is correct?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : Hydrogen is the most abundant element in the Universe,but it is not the most abundant gas in the troposphere.
Reason $R$ : Hydrogen is the lightest element.
In the light of the above statements,choose the correct answer from the options given below:

In the production of hydrogen by the Bosch process,which of the following is used as a catalyst?

Observe the following reactions:
$I$. $CO_{(g)} + H_{2(g)} \xrightarrow{X} HCHO_{(g)}$
$II$. $CO_{(g)} + 3 H_{2(g)} \xrightarrow{Y} CH_{4(g)} + H_2O_{(g)}$
The catalysts $X$ and $Y$ in the above reactions are respectively:

Which of the following is true for the industrial production of hydrogen from water gas $(CO + H_2)$?