Question

Two elements ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Y}^{\prime }$ have the following configurations
$X=1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^2$
$Y=1s^{2}2s^{2}2p^{6}3s^{2}3p^5$
The compound formed by the combination of ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Y}^{\prime }$ will be

• A. $X{Y}_2$
• B. $X_5{Y}_2$
• C. $X_2{Y}_5$
• D. $X{Y}_5$

Answer 1

The correct option is A $X{Y}_2$

The compound formed by combination of $X$ and $Y$ is ${XY}_2$ or ${\left[X\right]}^{2+}{\left[2Y\right]}^{-}$. $X$ has two electrons in its valence and $Y$ needs 1 electron to complete its octet.Thus one electron of $X$ is left which can be transfered to another $Y$ atom forming ${XY}_2$.