Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$NaH_{(s)} + H_2O_{(l)} \longrightarrow NaOH_{(aq)} + H_{2(g)} \uparrow$

Copper in an alloy is estimated by dissolving in conc. nitric acid. In this process,copper is converted to cupric nitrate with the evolution of nitric oxide $(NO)$. The mixture when treated with potassium iodide forms cupric iodide,which is unstable and decomposes to cuprous iodide and iodine. The amount of copper in the alloy is estimated by titrating the liberated iodine with sodium thiosulphate. The reactions are:
$a \,Cu + b \,HNO_3 \rightarrow c \,Cu(NO_3)_2 + d \,NO + e \,H_2O$
$f \,CuI_2 \rightarrow g \,Cu_2I_2 + h \,I_2$
$i \,Na_2S_2O_3 + j \,I_2 \rightarrow k \,Na_2S_4O_6 + l \,NaI$
(Fill in the blanks)
$(a)$ The coefficients are: $a=\ldots, b=\ldots, c=\ldots, d=\ldots$ and $e=\ldots$.
$(b)$ The coefficients are: $f=\ldots, g=\ldots$ and $h=\ldots$.
$(c)$ The coefficients are: $i=\ldots, j=\ldots, k=\ldots$ and $l=\ldots$.
$(d)$ If $2.54 \,g$ of $I_2$ is evolved from a $2.0 \,g$ sample of the alloy,what is the percentage of copper in the alloy? (Atomic weights of iodine and copper are $127$ and $63.5$,respectively).

Bromine water reacts with $SO_2$ to form

When $10 \, mL$ of an aqueous solution of $KMnO_{4}$ was titrated in acidic medium,an equal volume of $0.1 \, M$ aqueous solution of ferrous sulphate was required for complete discharge of colour. The strength of $KMnO_{4}$ in grams per litre is $...... \times 10^{-2}$. (Nearest integer)
[Atomic mass of $K=39, Mn=55, O=16$]

Which of the following is not formed when $H_2S$ reacts with acidic $K_2Cr_2O_7$ solution?

Assign $A, B, C, D$ from the given type of reaction.
$Ba(OH)_2 + CO_2 \longrightarrow BaCO_3 \downarrow + H_2O$