What is the time taken for the $3^{rd}$ half-life of a second-order decomposition reaction,given that its first half-life is $20 \ s$ (in $s$)?

For the reaction $aA + bB \to$ product,the rate of reaction is given by $Rate = k[A]^3 [B]^0$. If the concentration of $A$ is doubled and the concentration of $B$ is halved,the rate of reaction will be: (in $\times$)

The mechanism for the reaction is given below:
$2P + Q \to S + T$
$P + Q \to R + S$ (slow)
$P + R \to T$ (fast)
The rate law expression for the reaction is:

For a certain reaction $A \to P$,the half-life for different initial concentrations of $A$ is mentioned below:

$[A_0]$	$0.1 \ M$	$0.025 \ M$
$t_{1/2} \ (s)$	$100 \ s$	$50 \ s$

Which of the following option$(s)$ is/are correct?

For the following homogeneous reaction scheme,the rate constant has units for the reaction $A + B \xrightarrow{K} C$:

For the reaction: $2A + B \to A_2B$; the rate $= K[A][B]^2$ with $K = 2.0 \times 10^{-6} \ L^2 \ mol^{-2} \ s^{-1}$. Initial concentrations of $A$ and $B$ are $[A]_0 = 0.2 \ mol/L$ and $[B]_0 = 0.4 \ mol/L$ respectively. Calculate the rate of reaction after $[A]$ is reduced to $0.12 \ mol/L$.