Which of the following statements is not correct?

Options

A. A metal crystal lattice consists of positive kernels (metal ions left after the removal of valence electrons) arranged in a definite pattern in a sea of mobile electrons.
B. Each kernel (metal ion) is simultaneously attracted by a number of mobile electrons and each mobile electron is attracted by a number of metal ions.
C. van der Waals radius of an element is always shorter than its covalent radius.
D. A metallic radius is always longer than its convalent radius.

Answer

C

Explanation

Since van der Waals forces are weakes than the convalent bonds, and during the formation of convalent bonds the electron clouds overlap, covalent radii are always smaller than the van der Waals radii.
The mutual force of attraction between the mobile electrons and the positive kernels is called the metallic bond. it is weakes than the covalent bond. covalent radius of a metal is usually determined from its vapors which probably exist as usually moleculeus.