Glass is

The cubic unit cell structure of a compound containing cation $\mathrm{M}$ and anion $\mathrm{X}$ is shown below. When compared to the anion, the cation has smaller ionic radius. Choose the correct statement(s).

In the following circuit diagram, the current through the battery is

Match the following

        List - I                                      List-II
A) Metallic solid                         I) Carbon tetrachloride
B) Covalent solid                       II) Calcium fluoride
C) Molecular solid                     III) Copper
D) Ionic solid                             IV) Silicon carbide
                                                   V) Glass

The correct answer is

Given below are two statements. One is labelled as
Assertion $\mathrm{A}$ and the other is labelled as Reason $\mathrm{R}$.
Assertion $\mathrm{A}:$ Sharp glass edge becomes smooth on heating it up to its melting point.

Reason $\mathrm{R}:$ The viscosity of glass decreases on melting.

Choose the most appropriate answer from the options given below.