Question

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

• A. $X_2O$
• B. $XO$
• C. $XO_2$
• D. $X_2O_3$

Answer 1

Answer: (A)

$X_2O$

Answer 2

Element $X$ has atomic number $19$. Its valency will be one. Hence, the formula of its oxide will be $X_2O$. $Z = 19$; $1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6\, 4s^1$