Which of the following elements forms a covalent electron-deficient hydride?

Which of the following statements are correct?
$(i)$ $NaH_{(s)}$ reacts violently with water to form $NaOH$ and $H_2$
$(ii)$ An example for electron rich hydride is $NH_3$
$(iii)$ Nickel forms saline hydride

Which statement is not correct for ortho and para hydrogen?

Metals like $Pt$ and $Pd$ can adsorb large volumes of hydrogen under specific conditions. Such adsorbed hydrogen by the metal is known as:

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

Discuss the consequence of high enthalpy of $H-H$ bond in terms of chemical reactivity of dihydrogen.