Which of the following is the strongest acid?

The increasing order of the reactivity of the following compounds with $LiAlH_4$ is:
$(a)$ $C_2H_5CONH_2$
$(b)$ $C_2H_5COOCH_3$
$(c)$ $C_2H_5COCl$
$(d)$ $(C_2H_5CO)_2O$

Identify $X, Y$ and $Z$ respectively in the following reaction sequence:
$CH_3COOH$ $\xrightarrow[(ii) \Delta]{(i) NH_3} CH_3CONH_2$ $\xrightarrow[Pyridine / 343 \ K]{(iii) C_6H_5SO_2Cl} X + Y + Z$

Compound$(s)$ which will liberate carbon dioxide with sodium bicarbonate solution is/are:
$A = \text{2,4,6-triamino phenol}$
$B = \text{Benzoic acid}$
$C = \text{Picric acid (2,4,6-trinitrophenol)}$

Identify $X$ and $Y$ in the following reactions:

The dehydration of malonic acid $CH_2(COOH)_2$ with $P_4O_{10}$ gives: