What is the slope of the graph plotted between half-life $(t_{1/2})$ and initial concentration $(a)$ for a $1^{st}$ order reaction?

Azo isopropane decomposes according to the equation:
$((CH_3)_2CHN)_2N_{2(g)} \xrightarrow{250 - 290 \ ^oC} N_{2(g)} + C_6H_{14(g)}$
It is found to be a first order reaction. If the initial pressure is $P_o$ and the total pressure of the mixture at time $t$ is $P_t$,then the rate constant $K$ is given by:

If the concentration of the reactant increases by '$x$' for a first-order reaction,then $K = $?

The value of rate constant for a first order reaction is $2.303 \times 10^{-2} \text{ s}^{-1}$. What will be the time required to reduce the concentration to $\frac{1}{10}$th of its initial concentration (in $\text{ s}$)?

For a first-order reaction,the rate constant is $4 \times 10^{-3} \, s^{-1}$. If the concentration of the reactant is $0.02 \, M$,what will be the rate of the reaction?

The half-life period for a first-order reaction is . . . . . . .