$CH_3-CH_2-O-CH_2-CH_3$ and $CH_3-O-CH_2-CH_2-CH_3$ are

Identify the relationship between the following two compounds: $C_6H_5COOH$ and $o-HOC_6H_4CHO$.

Explain the following terms:
$(a)$ Isomerism
$(b)$ Position isomerism
$(c)$ Chain isomerism
$(d)$ Functional group isomerism
$(e)$ Metamerism
$(f)$ Optical isomerism

Isopentane and neopentane exhibit which type of isomerism?

The order of stability of the following tautomeric compounds is:
$(I) CH_2=C(OH)-CH_2-C(=O)-CH_3$
$(II) CH_3-C(=O)-CH_2-C(=O)-CH_3$
$(III) CH_3-C(OH)=CH-C(=O)-CH_3$

How many cyclic isomers are possible for ${C_5}{H_{10}}$?