Which of the following is a primitive unit cell?

Which of the following elements has a simple cubic lattice structure in its solid state?

Which of the following is not true about the amorphous solids?

Which of the following substances is useful for making permanent magnets?

$A$ solid which is very hard,has a very high melting point in the solid state,is an insulator,and becomes a conductor of electricity in its molten state is a/an ..... solid.

Molecules/ions and their magnetic properties are given below.

Molecule/ion	Magnetic property
$(i). C_6H_6$	$(1).$ Antiferromagnetic
$(ii). CrO_2$	$(2).$ Ferrimagnetic
$(iii). MnO$	$(3).$ Ferromagnetic
$(iv). Fe_3O_4$	$(4).$ Paramagnetic
$(v). Fe^{3+}$	$(5).$ Diamagnetic

The correctly matched pairs are: