A(g) $$\to$$ 2B(g) + C(g) is a first order reaction. The initial pressure of the system was found to be 800 mm Hg which increased to 1600 mm Hg after 10 min. The total pressure of the system after 30 min will be _________ mm Hg. (Nearest integer)

$$\mathrm{t}_{87.5}$$ is the time required for the reaction to undergo $$87.5 \%$$ completion and $$\mathrm{t}_{50}$$ is the time required for the reaction to undergo $$50 \%$$ completion. The relation between $$\mathrm{t}_{87.5}$$ and $$\mathrm{t}_{50}$$ for a first order reaction is $$\mathrm{t}_{87.5}=x \times \mathrm{t}_{50}$$ The value of $$x$$ is ___________. (Nearest integer)

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 ___________.