Which of the following elements mostly form covalent compounds?

Step-by-step solution

First member of 1 st group i.e. lithium, mostly form covalent compounds due to its small size and comparatively high I . E . (with respect to other members of its group). Covalent character depends upon the atomic radii. Smaller the atomic radii, more the covalent character i.e. the covalent character is inversely proportional to atomic radii.