A solution of 5 g nonvolatile solute in 50 g water decreases its freezing point by 0.2 K . Calculate the molar mass of solute if $\mathrm{K}_{\mathrm{f}}$ of water is $1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$.

Identify polyamide polymer from following.

If $r=k[A]^2[B]$ is rate law equation for reaction $\mathrm{A}+\mathrm{B} \rightarrow \mathrm{C}$, at $[\mathrm{A}]=1 \mathrm{M}$ and $[\mathrm{B}]=0.2 \mathrm{M}$, Calculate rate of reaction if rate constant is $6.25 \mathrm{M}^{-2} \mathrm{~s}^{-1}$.