Velocity constant $K$ of a reaction is affected by

Consider the following reaction $A + B \rightarrow C$.
The time taken for $A$ to become $1/4$ of its initial concentration is twice the time taken to become $1/2$ of the same. Also,when the change of concentration of $B$ is plotted against time,the resulting graph gives a straight line with a negative slope and a positive intercept on the concentration axis. The overall order of the reaction is . . . . .

For the reaction $A + B \rightarrow \text{Product}$,if the concentration of $A$ is doubled,the reaction rate doubles. When the concentration of $B$ is doubled,the reaction rate remains unchanged. What is the overall order of the reaction?

For the reaction,$H_{2(g)} + Br_{2(g)} \longrightarrow 2 HBr_{(g)}$,$r = k[H_2][Br_2]^{\frac{1}{2}}$. What is the molecularity and order of reaction respectively?

The differential form of the rate equation is given by:
$dx/dt = k[P][Q]^{0.5}[R]^{0.5}$
Which statement about the above equation is wrong?

Consider a reaction $aG + bH \rightarrow$ Products. When the concentration of both reactants $G$ and $H$ is doubled,the rate increases by $8$ times. However,when the concentration of $G$ is doubled keeping the concentration of $H$ fixed,the rate is doubled. The overall order of the reaction is: