Given below are the critical temperatures of some of the gases:

The gas showing least adsorption on a definite amount of charcoal is

In liquation process used for tin (Sn), the metal :

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'?