Match List -I with List - II.
$\begin{array}{cccc}& \text{List-I}& & \text{List-II}\\ & \text{(Hydrides)}& & \text{(Nature)}\\ \text{(a)}& Mg{H}_2& \text{(i)}& \text{Electron precise}\\ \text{(b)}& Ge{H}_4& \text{(ii)}& \text{Electron deficient}\\ \text{(c)}& B_2{H}_6& \text{(iii)}& \text{Electron rich}\\ \text{(d)}& HF& \text{(iv)}& \text{Ionic}\end{array}$
Choose the correct answer from the options given below.

1. (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)
2. (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii)
3. (a) – (iii), (b) – (i), (c) – (ii), (d) – (iv)
4. (a) – (i), (b) – (ii), (c) – (iv), (d) – (iii)

The correct option is B (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii)
Compounds of hydrogen with less electronegative elements are known as hydrides.
Hydrides are mainly divided into three major types or groups, based on what elements the hydrogen forms bonds with. The three types of hydrides are ionic, covalent, and metallic hydrides. Ionic or Saline Hydrides

They are formed when hydrogen molecule reacts with highly electropositive s-block elements (Alkali Metals and Alkaline Earth Metals). For example : $NaH$, $KH$, $Ca{H}_2$ etc.

Covalent Hydrides (which have $H$ bonded to non-metals through covalent bonds) are of three types on the basis of relative number of electrons and bonds in their Lewis structure :

(i) Electron-deficient hydride : Elements of group 13 will form electron-deficient hydrides. They act as Lewis acids, e.g., $B_2{H}_6$.
(ii) Electron-precise hydride : All elements of group 14 form electron-precise hydrides, e.g., $C{H}_4$.
(iii) Electron-rich hydride : Elements of group 15-17 form such compounds. They act as Lewis bases, e.g., $N{H}_3$.

$Mg{H}_2\to$ Ionic
$Ge{H}_4\to$ electron precise
$B_2{H}_6\to$ electron deficient
$HF\to$ electron rich