Which of the following statement is incorrect ?

Options

A. The atomic radius of `Na` is greater than that of `Mg`
B. Metallic bond in `Mg` is stronger than the metallic bond in `Na`
C. Melting and boiling points of `Mg` are greater than those of `Ca`
D. `Mg` and `Ca` both impart characteristic colour to the flame

Answer

D

Explanation

`(a)` Along the period, the nuclear charge increases and, therefore, atomic size decreases, So `Na` has larger atomic radius than `Mg`.
`(b) Mg` is smaller than `Na` and `Mg` has two valence electrons per atom while `Na` has only one valence electron per atom. So `Mg` has stronger metallic bond than that of `Na(Na` is a soft metal `).`
`(c)` Because of stronger metallic bond in `Mg` than `Ca`, boiling and melting point of `Mg` are greater than `Ca`.
`(d) Mg` does not impart characteristic colour to the flame because the electrons in `Mg` are too strongly bound to get excited by flame. `Ca` imparts brick red colour to the flame because of its low ionisation enthalpy.