With the increase in atomic weights,the melting points of the alkali metals:

The element having electronic configuration $[Kr]4d^{10} 4f^{14} 5s^2 5p^6 6s^2$ belongs to

Which of the following metal carbides is known as a methanide?

Why is $lithium$ superoxide $(LiO_2)$ not possible?

The causticization process is used for the preparation of:

$A$ metal $(A)$ on heating in nitrogen gas gives compound $(B)$. $(B)$ on treatment with $H_{2}O$ gives a colourless gas which when passed through $CuSO_{4}$ solution gives a dark blue-violet coloured solution. $(A)$ and $(B)$ respectively,are