Chemical Kinetics question bank (Chemistry)

For a first order reaction, (A) $\rightarrow$ Products, the concentration of A changes from $0.1$ M to $0.025$ M in $40$ minutes. The rate of reaction when the concentration of A is $0.01$ M is

The combination of $\text{NO}_2(g)$ and $\text{CO}(g)$ occurs in two steps as follows: What is the rate law for the reaction?
$2\text{NO}_2 \rightarrow \text{NO} + \text{NO}_3$ $(k_1)$ - slow
$\text{NO}_3 + \text{CO} \rightarrow \text{CO}_2 + \text{NO}_2$ $(k_2)$ - fast