The energy of an electron in the first Bohr's orbit of $H$ atom is $-13.6 \ eV$. The possible energy value$(s)$ of the excited state$(s)$ for an electron in Bohr's orbits of hydrogen is (are): ............. $eV$

In which of the following reactions,chlorine acts as an oxidising agent?
$(i)$ $CH_3CH_2OH + Cl_2 \longrightarrow CH_3CHO + HCl$
$(ii)$ $CH_3CHO + Cl_2 \longrightarrow CCl_3CHO + HCl$
$(iii)$ $CH_4 + Cl_2 \xrightarrow{hv} CH_3Cl + HCl$
The correct answer is

Let $f: R \rightarrow R$ be a function such that $f(x)=x^3+x^2 f^{\prime}(1)+x f^{\prime \prime}(2)+6, x \in R$,then $f(2)$ equals

Choose the correct option regarding the following complex compounds which follows $(F)$ and does not follow $(NF)$ the Sidgwick $EAN$ rule:
$(I) \ [(Ph_3P)_2PdCl_2]$
$(II) \ [NiBrCl(en)]$
$(III) \ Na_4[Fe(CN)_5NOS]$
$(IV) \ Cr(CO)_3(NO)_2$
$(I) - (II) - (III) - (IV)$

The Vernier scale of a travelling microscope has $50$ divisions which coincide with $49$ main scale divisions. If each main scale division is $0.5 \text{ mm}$,then the least count of the microscope is

The work functions for tungsten and sodium are $4.5 \ eV$ and $2.3 \ eV$ respectively. If the threshold wavelength for sodium is $5460 \ \mathring{A}$,then the threshold wavelength for tungsten is .......... $\mathring{A}$.