Given below are two statements.

Statement I : Stannane is an example of a molecular hydride.

Statement II : Stannane is a planar molecule.

In the light of the above statement, choose the most appropriate answer from the options given below.

Portland cement contains 'X' to enhance the setting time. What is 'X'?

When borax is heated with $$\mathrm{CoO}$$ on a platinum loop, blue coloured bead formed is largely due to :

Which of the following $$3\mathrm{d}$$-metal ion will give the lowest enthalpy of hydration $$\left(\Delta_{\text {hyd }} \mathrm{H}\right)$$ when dissolved in water ?