The graphical variation of molar conductivity $(\Lambda)$ against square root of molar concentration $(\sqrt{c})$ of certain electrolyte 'X' is linear with intercept on y axis. Identify X from following.

If standard reduction potential $(E^0)$ of $\left(\text{Al}^{+3}_{(aq)}|\text{Al}_{(s)}\right)$, $\left(\text{Fe}^{+2}_{(aq)}|\text{Fe}_{(s)}\right)$, $\left(\text{Cu}^{+2}_{(aq)}|\text{Cu}_{(s)}\right)$ and $\left(\text{Ag}^{+1}_{(aq)}|\text{Ag}_{(s)}\right)$ are $-1 \cdot 66$ V, $-0 \cdot 44$ V, $+0 \cdot 34$ V and $+0 \cdot 79$ V respectively. Which of the following reaction is non spontaneous ?

For the reaction $2\text{NOBr}_{(g)} \rightarrow 2\text{NO}_{(g)} + \text{Br}_{2(g)}$ rate law is $r = k[\text{NOBr}]^2$, if rate constant is $1 \cdot 62 \text{ mol dm}^{-3}\text{ s}^{-1}$ and concentration of NOBr is $2 \times 10^{-3} \text{ mol L}^{-1}$. What is the rate of reaction ?

In first order reaction 20 millimole of reactant is reduced to 10 millimole in $1 \cdot 151$ minute. Find rate constant.