If the concentration of a first-order reaction is increased by $x$ times,then the rate constant $(k)$ becomes

Which one of the following is wrong about molecularity of a reaction?

What will be the unit of the rate constant for the following reaction?
$C_2H_{4(g)} + H_{2(g)} \rightarrow C_2H_{6(g)}$

Rate of reaction is $r_1 = k[A]^a[B]^b$. If the concentration of $A$ is doubled and $B$ is halved,the new rate is $r_2$. What is the value of $\frac{r_2}{r_1}$?

Define the following terms:
$(1)$ Rate law / Rate equation / Rate expression
$(2)$ Unimolecular reaction

State whether the following sentences are true $(T)$ or false $(F)$:
$(a)$ There is more than one reactant in a pseudo first order reaction.
$(b)$ In a pseudo first order reaction,the concentration of both reactants is the same.
$(c)$ In a pseudo first order reaction,the concentration of one reactant is very high.