Classification of elements and Periodicity in properties MCQs for NEET — Chemistry Questions with Answers

Halogens can mutually displace each other from the solution of their compounds with metals. This property is based on their relative reactivity: a more reactive halogen can displace a less reactive halogen from its compounds. For example, chlorine can displace bromine and iodine from their salts.

The bond dissociation energy decreases down the group in halogens. This is because the atomic size increases, leading to a longer bond length and weaker bond strength. Therefore, the correct order of bond dissociation energy should be $ I_2 extgreater Br_2 extgreater Cl_2 extgreater F_2 $. Hence, the order given in option o2 is not proper.

Fluorine does not show higher oxidation states because it lacks d-orbitals. All other halogens can utilize their d-orbitals to achieve higher oxidation states, but fluorine, being in the second period, has no d-orbitals available. Therefore, the correct answer is 'It has no d-orbital'.

$ Ar_{18} \rightarrow 2, 8, 8 $

$ Ne_{10} \rightarrow 1S^2, 2S^2 2P^6 $

He is least polarizable bec. Of small size.

Melting point decreases as the strength of metallic bonding decreases with increasing size of the atom.

Thermal stability of metal carbonates increases as the electropositive character of the metal or the basicity of the metal hydroxide increases from $ Be(OH)_2 to Ba(OH)_2, Thus, BaCO_3 $ is the most stable.

As the ionisation enthalpy increases from $ Mg \rightarrow Ba $ the M - O bond becomes weaker and weaker down the group, and hence basicity increases down the group. Thus, $ Mg(OH)_2 $ is least basic.