The reaction $$2 \mathrm{NO}+\mathrm{Br}_{2} \rightarrow 2 \mathrm{NOBr}$$

takes places through the mechanism given below:

$$\mathrm{NO}+\mathrm{Br}_{2} \Leftrightarrow \mathrm{NOBr}_{2}$$ (fast)

$$\mathrm{NOBr}_{2}+\mathrm{NO} \rightarrow 2 \mathrm{NOBr}$$ (slow)

The overall order of the reaction is ___________.

An analyst wants to convert $$1 \mathrm{~L} \mathrm{~HCl}$$ of $$\mathrm{pH}=1$$ to a solution of $$\mathrm{HCl}$$ of $$\mathrm{pH} ~2$$. The volume of water needed to do this dilution is __________ $$\mathrm{mL}$$. (Nearest integer)

One mole of an ideal gas at $$350 \mathrm{~K}$$ is in a $$2.0 \mathrm{~L}$$ vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from 2.0 L to $$3.0 \mathrm{~L}$$ against a constant pressure of $$4 \mathrm{~atm}$$. The change in entropy of the surroundings ( $$\Delta \mathrm{S})$$ is ___________ $$\mathrm{J} \mathrm{K}^{-1}$$ (Nearest integer)

Given: $$\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$.

Two dice A and B are rolled. Let the numbers obtained on A and B be $$\alpha$$ and $$\beta$$ respectively. If the variance of $$\alpha-\beta$$ is $$\frac{p}{q}$$, where $$p$$ and $$q$$ are co-prime, then the sum of the positive divisors of $$p$$ is equal to :