What is the wavenumber of the photon emitted during transition from the orbit $\mathrm{n}=5$ to that of $\mathrm{n}=2$ in hydrogen atom? $\left[\mathrm{R}_{\mathrm{H}}=109677 \mathrm{~cm}^{-1}\right]$

If pH of solution changes from 4 to 5 , then the $\mathrm{H}_3 \mathrm{O}^{+}$ion concentration of solution

The last column in the truth table of the statement pattern $[\mathrm{p} \rightarrow(\mathrm{q} \wedge \sim \mathrm{p})] \vee[(\mathrm{p} \vee \sim \mathrm{q}) \wedge \mathrm{p}]$ is

A straight line through the origin $O$ meets the line $3 y=10-4 x$ and $8 x+6 y+5=0$ at the points $A$ and B respectively. Then O divides the segment $A B$ in the ratio