The correct order of reactivity of $PhMgBr$ with: $(I)$ $Ph-CO-Ph$,$(II)$ $CH_3-CHO$,$(III)$ $CH_3-CO-CH_3$ is:

Identify $A, B$ and $C$ in the following reactions:
$CH_3 Cl$ $\xrightarrow{KCN} A$ $\xrightarrow{H_3 O^{\oplus}} B$ $\xrightarrow{C_2 H_5 OH / H^{+}, \Delta} C$

If the kinetic energy of a body is directly proportional to time $t$,the magnitude of force acting on the body is
$(i)$ directly proportional to $\sqrt{t}$
$(ii)$ inversely proportional to $\sqrt{t}$
$(iii)$ directly proportional to the speed of the body
$(iv)$ inversely proportional to the speed of the body

The solubility of barium iodate in an aqueous solution prepared by mixing $200 \ mL$ of $0.010 \ M$ barium nitrate with $100 \ mL$ of $0.10 M$ sodium iodate is $X \times 10^{-6} mol dm ^{-3}$. The value of $X$ is $.....$
Use: Solubility product constant $\left(K_{ sp }\right)$ of barium iodate $=1.58 \times 10^{-9}$

At $27^{\circ} C$,$500 \ mL$ of helium diffuses in $30 \ minutes$. What is the time (in hours) taken for $1000 \ mL$ of $SO_2$ to diffuse under the same experimental conditions?

Which of the following pairs of elements cannot form an alloy?