If the electronic configuration of an element is $1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^2 4 s^2$, the four electrons involved in chemical bond formation will be

Which of the following angle corresponds to sp$$^2$$ hybridisation?

$$\begin{array}{llllll} A & 1 s^2 & 2 s^2 & 2 p^6 & & \\ B & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^3 \\ C & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^5 \end{array}$$

Stable form of $A$ may be represented by the formula

$$\begin{array}{llllll} A & 1 s^2 & 2 s^2 & 2 p^6 & & \\ B & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^3 \\ C & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^5 \end{array}$$

Stable form of $C$ may be represented by the formula

$$\begin{array}{llllll} A & 1 s^2 & 2 s^2 & 2 p^6 & & \\ B & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^3 \\ C & 1 s^2 & 2 s^2 & 2 p^6 & 3 s^2 & 3 p^5 \end{array}$$

The molecular formula of the compound formed from $B$ and $C$ will be