Correct Answer - 4
Hydrogen can combine with other elements by losing, gaining and sharing of electrons.
`(i)` Losing of electron `:H_(2)+F_(2)rarr2H^(+)F^(-)`
`(ii)` Gaining of electrons `:2Na+H_(2)rarr2Na^(+)H^(-)`
`(iii)` Sharing of electrons `:N_(2)+3H_(2)underset(underset("High pressure")(500^(@)C))overset(Fe+MO)rarr2NH_(3)`
`C+2H_(2)overset(1200^(@)C)rarrCH_(4)`