Question

Match the entries in column I with the entries in column II.
$$\begin{array}{cc}\text{Elements}& \text{Electronic configuration}\\ \text{(i)}{C}^{-4}\text{is highly unstable because}& \text{(a) It would be difficult for carbon with six protons in its nucleus to hold on just two electrons.}\\ \text{(ii)}{C}^{+4}\text{is achieved by}& \text{(b) gaining four electrons to its outermost orbit}\\ \text{(iii)}{C}^{+4}\text{is highly unstable because}& \text{(c) losing four valence electrons}\\ \text{(iv)}{C}^{-4}\text{is achieved by}& \text{(d) It is difficult for the nucleus with six protons to hold on ten electrons, i.e. four extra electrons}\end{array}$$

• A. 1- d, 2-c, 3-a and 4-b
• B. 1- d, 2-c, 3-b and 4-a
• C. 1- b, 2-a, 3-c and 4-d
• D. 1- c, 2-a, 3-d and 4-b

Answer 1

The correct option is A

1- d, 2-c, 3-a and 4-b

In case of C^-4, the number of electrons in the outer most orbit is 8.Thus the total number of electrons including 2 electrons in the inner orbit is 10. But the number of protons still remains the same .i.e. 6. Thus it becomes difficult for 6 protons to hold back 10 electrons.

C⁺⁴ is achieved by losing 4 more electrons from the outermost orbit. In this case, the number of electrons in the outermost orbit is 2. Thus, the total number of electrons is 2 but the number of protons is the same i.e. 6. Thus, force of attraction between 6 protons and 2 electrons becomes too high, which leads to unstable carbon atom.