What is the chemical formula for calcium cyanamide?

Excess of $Na^{+}$ ions in our system causes:

The alkali metals form salt-like hydrides by direct synthesis at elevated temperatures. The thermal stability of these hydrides decreases in which of the following orders?

$A$ compound $(M_2O_2)$ of group $I$ element $(M)$ hydrolyses to form $M^{+}$,$OH^{-}$ and $X$. Another compound $(M'O_2)$ of group $I$ element $(M')$ hydrolyses to form $(M')^{+}$,$OH^{-}$,$X$ and $Y$. What are $X$ and $Y$ respectively?

Number of amphoteric compounds among the following is ...........
$A$. $BeO$
$B$. $BaO$
$C$. $Be(OH)_2$
$D$. $Sr(OH)_2$

In which of the following reactions is hydrogen gas not liberated?