An element 'X' has atomic number 13 : (a) Write its electron configuration. (b) State the group to which 'X' belongs ? (c) Is 'X' a metal or a non-metal ? (d) Write the formula of its bromide.

(a) Electronic Configuration:

The electronic configuration of element $\text{X}$ (Atomic number 13) is $2, 8, 3$.

(b) Group Number:

Element $\text{X}$ belongs to Group 13 of the Modern Periodic Table.

(Reason: Since it has 3 valence electrons, its group number is $10 + 3 = 13$.)

(c) Metal or Non-metal:

$\text{X}$ is a metal.

(Reason: It has 3 valence electrons in its outermost shell, which it can easily lose to form a stable positive ion/cation, $\text{X}^{3+}$.)

(d) Formula of its Bromide:

The valency of $\text{X}$ is $3$ and the valency of Bromine ($\text{Br}$) is $1$. By crossing over their valencies:

$$\text{Formula} = \text{XBr}_3$$