The unit of the rate constant for a second-order reaction is ....

$2 \ FeCl_3 + SnCl_2 \rightarrow 2 \ FeCl_2 + SnCl_4$. This reaction is an example of:

The rate constants for the following reactions are:
Reaction $1$: $A \xrightarrow{\text{catalyst } 1} P_1, k_1 = 1 \ s^{-1}$
Reaction $2$: $A \xrightarrow{\text{catalyst } 2} P_2, k_2 = 0.1 \ L \ mol^{-1} \ s^{-1}$
Reaction $3$: $A \xrightarrow{\text{catalyst } 3} P_3, k_3 = 0.01 \ L^2 \ mol^{-2} \ s^{-1}$
What is the correct relation between the rates of the reactions at $[A] = 1 \ M$?

What is the molecularity of a reaction? Explain its types with examples.

Which of the following is an example of a second-order reaction?

$A$ reaction $A + B \rightarrow C$ is second order in $A$ and zeroth order in $B$. How is the rate affected when the concentration of $A$ is doubled and $B$ is halved?