Question

Statement 1 (S1): The valencies of calcium and bromide ions are 1 and 2 respectively.
Statement 2 (S2): The chemical formula of the compound formed by one calcium and two bromide ions is $CaB{r}_2$.

Answer 1

Valency of ${Ca}^{2+}$ ion is 2 as it carries +2 charge.
Valency of ${Br}^{-}$ ion is 1 as it carries -1 charge.

Thus, S1 is false.

For writing the chemical formula of the compound:

Symbol	Ca	Br
Valency	2	1

Upon criss-crossing the valencies, we get the formula of the compound as $Ca{Br}_2$.

Thus, S2 is true.