Question

In which of the following, the order is not in accordance with the property mentioned?

• A. $Li<Na<K<Rb$ - Atomic radius
• B. $F>N>O>C$- Ionisation enthalpy
• C. $Si<P<S<Cl$ - Electronegativity
• D. $F<Cl<Br<I$ - Electronegativity

Answer 1

Answer: (D)

$F<Cl<Br<I$ - Electronegativity

Atomic radius increases down the group as the shell size increases. In group 1 order is: $Li<Na<K<Rb<Cs$

Ionization enthalpy increases from left to right in a period due to an increase in effective nuclear charge. Due to the extra stability of fully filled and half-filled configurations ionization of $N>O$ and the order is thus $F>N>O>C$

Electronegativity increases from left to right and decreases from top to bottom. Thus in group 3, we have the order: $Si<P<S<Cl$ and $F>Cl>Br>I$.

Electronegativities of halogens are not in correct order. Hence, the answer is option $D$.