Among formic acid,acetic acid,propanoic acid and phenol,the strongest acid in water is

The acid strength of the active methylene group in
$(a)$ $CH_3COCH_2COOC_2H_5$
$(b)$ $CH_3COCH_2COCH_3$
$(c)$ $C_2H_5OOCCH_2COOC_2H_5$
decreases as:

Which of the following reactions produce carboxylic acids?
$(a)$ $MnO_2$ with $CH_3COCH_3$
$(b)$ $Ph-CCl_3 \xrightarrow[(ii) H_2O/H^+]{(i) aq. NaOH} PhCOOH$
$(c)$ $C_2H_5Br \xrightarrow[(iii) H_2O/H^+]{(i) Mg, (ii) CO_2} C_2H_5COOH$
$(d)$ $CH_3CH=CHCH_3 \xrightarrow[\Delta]{K_2Cr_2O_7/H_2SO_4} 2CH_3COOH$

Identify the correct option based on the following reaction sequence:
Acetic anhydride $\xrightarrow[(ii) EtOH/H^+/\Delta]{(i) H_3O^+} (A)$ $\xrightarrow[(ii) H_3O^+/\Delta]{(i) NaOEt} (B)$

When compound $X$ is oxidised by acidified potassium dichromate,compound $Y$ is formed. Compound $Y$ on reduction with $LiAlH_4$ gives $X$. $X$ and $Y$ respectively are:

Compound $(B)$ is