Which of the following compounds is asymmetric?

Compounds $P$ and $R$ in the following reaction are:

$CH_3-CH_2-CH_2-COOH$ and $CH_3-CH(CH_3)-COOH$ are examples of:

Identify the correct statements from the following. Choose the correct answer from the options given below.
$A$. Pentan$-3-$one and Pentan$-2-$one are metamers.
$B$. Butanenitrile and Butaneisonitrile are functional isomers.
$C$. Butan$-1-$ol and Butan$-2-$ol are position isomers.
$D$. Butan$-1-$amine and $N$-methylpropan$-1-$amine are homologous.

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

Which of the following is an isomer of compound $(1)$?
$(1) \ CH_3CH_2CHO$
$(2) \ CH_3COCH_3$
$(3) \ CH_3CH=CHOH$
$(4) \ \text{2-methyloxirane (propylene oxide)}$