Question

Which of the following pairs show opposite trend on moving along a period from left to right and from top to bottom in a group ?

• A. Atomic radius and electron gain enthalpy (negative value)
• B. Nuclear charge and ionization enthalpy
• C. Ionization enthalpy and electron gain enthalpy (negative value)
• D. None of the above

Answer 1

The correct option is A Atomic radius and electron gain enthalpy (negative value)

(a) As we move across the period, atomic radius decreases, the negative value of electron gain enthalpy increases.
As we move from top to bottom in a group, atomic radius increases (as shell number increases), the negative value of electron gain enthalpy decreases.
(b) Ionisation energy and nuclear charge increases across the period from left to right.
(c) Ionisation enthalpy and electron gain enthalpy (negative value) increases across the period from left to right.
Thus, Atomic radius and electron gain enthalpy (negative value) show reverse properties on moving along a period from left to right and from top to bottom in a group