Identify the catalyst used to transform carbon monoxide from water gas into carbon dioxide.

An alkali metal hydride $(NaH)$ reacts with diborane in '$A$' to give a tetrahedral compound '$B$' which is extensively used as a reducing agent in organic synthesis. The compounds '$A$' and '$B$' respectively are

In $para-hydrogen$,what is the nature of the electron spin?

Which one of the following statements is incorrect $?$

Spin isomerism is shown by

Isotope$(s)$ of hydrogen which emits low energy $\beta^{-}$ particle with $t_{1/2}$ value $> 12 \ years$ is/are :