In non-cyclic photophosphorylation,the electron released by $PSI$ is accepted by ..........

The eccentricity of the ellipse $\frac{x^2}{16} + \frac{y^2}{9} = 1$ is

Five moles of hydrogen initially at $STP$ is compressed adiabatically so that its temperature becomes $673 \, K$. The increase in internal energy of the gas, in kilo joule is $(R=8.3 \, J/mol-K; \gamma=1.4$ for diatomic gas$)$

The $pH$ of the solution containing $10 \ mL$ of $0.1 \ N \ NaOH$ and $10 \ mL$ of $0.05 \ N \ H_2SO_4$ would be:

If a root of the equations $x^2+px+q=0$ and $x^2+\alpha x+\beta=0$ is common,then its value will be (where $p \neq \alpha$ and $q \neq \beta$)

The first,second and third Ionisation energies ($E_1, E_2$ and $E_3$) for an element are $7 \ eV, 12.5 \ eV$ and $42.5 \ eV$ respectively. The most stable oxidation state of the element will be