In cement composition,the main compound (by percentage) is?

Among alkali metals,which element do you expect to be least electronegative and why?

Which one of the following statements is correct?

The correct statements are:
$I$. The low solubility of $LiF$ is due to its high lattice enthalpy.
$II$. $LiBr$ is soluble in acetone.
$III$. $LiCl$ is soluble in pyridine.
$IV$. The order of melting points of alkali metal halides is $MF > MCl > MBr > MI$.

$A$ metal $M$ reacts with $N_2$ to give a compound '$A$' $(M_3N)$. '$A$' on heating at high temperature gives back '$M$' and '$A$' on reacting with $H_2O$ gives a gas '$B$'. '$B$' turns $CuSO_4$ solution blue on passing through it. $A$ and $B$ can be

In which of the following cannot sodium metal be stored?