Which chemical is used as a refrigerant in refrigerators?

Which hydride among the following is less stable?

The highest industrial consumption of molecular hydrogen is to produce compounds of element ...... .

The gaseous product$(s)$ expected at room temperature by the reaction of sodium borohydride and boron trifluoride under anhydrous conditions is/are:

The gas used in the hydrogenation of oils in the presence of nickel as a catalyst is

Ortho-hydrogen and para-hydrogen resemble in which of the following properties?