Taking the reaction $\mathrm{X}+2\mathrm{Y}\to$products to be of second order, which of the following is/are the rate law expression/s for the reaction

$1)\frac{\mathrm{dx}}{\mathrm{dt}}=K\left[X\right]\left[y\right]$

$II) \frac{\mathrm{dx}}{\mathrm{dt}}=K\left[X\right]{\left[y\right]}^{\mathit{2}}$

III)$\frac{\mathrm{dx}}{\mathrm{dt}}=K{\left[X\right]}^{\mathit{2}}$

IV)$\frac{\mathrm{dx}}{\mathrm{dt}}=K\left[X\right]\mathit{+}K{\left[y\right]}^{\mathit{2}}$

Then the correct answers can be