Question

An element $X$ has atomic number $19$. What will be the formula of its oxide?

• A. $X_{2}O$
• B. $XO$
• C. $X{O}_2$
• D. $X_2{O}_3$

Answer 1

Answer: (A)

Element $X$ has atomic number $19$. Its valency will be one. Hence, the formula of its oxide will be $X_{2}O$.
$Z=19$; $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$