Initial concentration of reactant in a first order reaction is $0.08 \mathrm{~mol} \mathrm{~dm}^{-3}$ What concentration would remain after 40 minute?

$$\left(\text { given } \frac{[\mathrm{A}]_0}{[\mathrm{~A}]_{\mathrm{t}}}=5.00\right)$$

Which from following amines has highest $\mathrm{pK}_{\mathrm{b}}$ value?

What is oxidation number of S in $\mathrm{SO}_3^{2-}$ ?

When fused NaCl undergoes electrolysis the product formed at cathode is