Which one of the following molecules does not show stereoisomerism?

What is the relationship between the two structures shown?

How many of the following molecules are meso compounds?

Which of the following pairs of compounds are not positional isomers?

Identify the correct sequence for True and False.
$(I)$ Only compounds with chiral centers can be optically active.
$(II)$ Absence of elements of symmetry is the reason for a molecule's optical activity.
$(III)$ All organic compounds contain carbon $\&$ hydrogen.
$(IV)$ Different canonical forms of a molecule represent the actual structures of a molecule which has resonance in it.

What is the relationship between the members of the following pairs of structures? Are they structural isomers,geometrical isomers,or resonance contributors?