Question

Electronic configurations of three elements,A,B and C are given below.

A: $1s^{2}2s^{2}2p^6$

B: $1s^{2}2s^{2}2p^{6}3s^{2}3p^3$

C: $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$

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

• A. $B{C}_3$
• B. $BC$
• C. $B_{2}C$
• D. $B{C}_2$

Answer 1

The correct option is A $B{C}_3$

Solution:

Element Electronic configuration


$B\left(P\right)$ $1s^{2}2s^{2}2p^{6}3s^{2}3p^3$


$C\left(CI\right)$ $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$

Valence shell electrons: Number of electrons in the outer shell of an atom are called valence shell electrons. These electrons take part in bond formation.

Octet rule: The elements form bond to complete 8 electrons in their valence shell.

'B' has 5 electrons in its valence shell, so it needs 3 electrons to complete its octet.

'C' has 7 electrons in its valence shell, so it needs 1 electron to complete its octet.

So, an atom of shares 1 electron each with 3 atoms of C, this way the octets of both are completed.



Since 1 atom of B combines with 3 atoms of C, molecular formula of the compound formed will be $B{C}_3$

Hence, option (D) is correct.