Question

Which statement is correct?
A. The electron affinity of carbon is more than that of oxygen
B. The electron affinity of sulphur is less than that of oxygen
C. The electron affinity of iodine is greater than that of bromine
D. The electron affinity of bromine is less than chlorine

Answer 1

Hint: Electron affinity is the tendency of an atom to attract electrons. Larger the size of the atom smaller will its tendency to attract another particle be. Atomic size increases down the group Out of the given options, try to determine the trend in change in atomic size.

Complete step by step answer:
Let us first understand the terms used in the question:
The electron affinity of an atom or molecule is defined as the amount of energy released when an electron is attached to a neutral atom or molecule in the gaseous state to form a negative ion.
so, A molecule or an atom that features a more positive value of electron affinity than another is usually called an electron acceptor and less positive an electron donor. Together they may undergo charge transfer reactions.
Electron affinity is the tendency for an atom to attract electrons to complete its octet. This tendency is basically the attractive force by which the protons will attract the incoming electrons. Hence, smaller the size, more is the effect of protons towards electrons. Hence, as doing down the group, the size increases, therefore the effect of the protons decreases, we can say that effective nuclear charge decreases.
Since carbon comes before oxygen, oxygen has a higher electron affinity
The electron affinity of bromine is less than the electron affinity of chlorine
On moving down the group, from chlorine to bromine to iodine, the electron affinity decreases.

So, the correct answer is Option D.

Note: Electron affinity is a qualitative value and has no mathematical magnitude. However, electron gain enthalpy is a quantitative value which can be assumed to be the mathematical representation of the energy released when an atom gains electrons. The higher this value, more electronegative will be the species.