The compounds $CH_3COCH_3$ and $CH_2=C(OH)CH_3$ exhibit which of the following?

Which of the following statements is wrong?

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

Which of the following is a pair of functional isomers?

$C_6H_5C \equiv N$ and $C_6H_5N \equiv C$ exhibit which type of isomerism?

Assertion $A$: Enol form of acetone $[CH_{3}COCH_{3}]$ exists in $< 0.1 \%$ quantity. However,the enol form of acetylacetone $[CH_{3}COCH_{2}COCH_{3}]$ exists in approximately $15 \%$ quantity.
Reason $R$: Enol form of acetylacetone is stabilized by intramolecular hydrogen bonding,which is not possible in the enol form of acetone. Choose the correct statement: