MOCK-1PAPER-1 Cambridge AS
5
Two conversions are outlined below.
NH. NHS
CH → CHE
What similar feature do these two conversions have?
A alone pair of electrons in the product
B change in oxidation state of an element
c decrease in bond angle of the species involved
D disappearance of a x bond

it is b that is the answer.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.