Product $(A)$ is

The correct order of ionisation energy of $C, N, O, F$ is :-

Which of the following is concerned with eubacteria?
$(1)$ Methanogens $(2)$ Anabaena $(3)$ $N_2$ fixation $(4)$ Thermoacidophiles $(5)$ Eukaryotes $(6)$ Diatoms $(7)$ Gelatinous sheath $(8)$ Heterocyst

The maximum value of $f(x) = x^4 e^{-x^2}$ is

If a hydrogen electrode is dipped in a solution of $pH = 3$ and $pH = 6$ and a salt bridge is connected,then the $emf$ of the resulting cell is ........... $V$.

An electronic transition in a hydrogen atom results in the formation of the $H_\alpha$ line of the hydrogen spectrum in the Lyman series. The energies associated with the electron in each of the orbits involved in the transition (in $kcal \ mol^{-1}$) are: