A bulb is rated at 150 watt, converting $8 \%$ energy into light. If energy of one photon is $4.42 \times 10^{-19} \mathrm{~J}$, how many photons are emitted by the bulb per second?

The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes $n=2 \rightarrow n=3$ and $n=4 \rightarrow$ $\mathrm{n}=6$ transitions, respectively, is

Energy and radius of first Bohr orbit of $\mathrm{He}^{+}$and $\mathrm{Li}^{2+}$ are [Given $\mathrm{R}_{\mathrm{H}}=2.18 \times 10^{-18} \mathrm{~J}, \mathrm{a}_0=52.9 \mathrm{pm}$ ]

The quantum numbers of four electrons are given below :

I. $$n=4 ; I=2 ; m_1=-2 ; s=-\frac{1}{2}$$

II. $$n=3 ; I=2 ; m_1=1 ; s=+\frac{1}{2}$$

III. $$n=4 ; I=1 ; m_1=0 ; s=+\frac{1}{2}$$

IV. $$n=3 ; I=1 ; m_1=-1 ; s=+\frac{1}{2}$$

The correct decreasing order of energy of these electrons is