The velocity associated with a proton moving in a potential difference of $1000 \mathrm{V}$ is $4.37\times {10}^5 {\mathrm{ms}}^{–1}$. If the hockey ball of mass $0.1\mathrm{kg}$ is moving with this velocity, calculate the wavelength associated with this velocity.

The quantum numbers of six electrons are given below. Arrange them in order of increasing energies. If any of these combination(s) has/have the same energy lists:

1. $\mathrm{n}=4, \mathrm{l}=2, {\mathrm{m}}_{\mathrm{l}}=–2, {\mathrm{m}}_{\mathrm{s}}=–1/2$
2. $\mathrm{n}=3, \mathrm{l}=2, {\mathrm{m}}_{\mathrm{l}}=1, {\mathrm{m}}_{\mathrm{s}}=+1/2$
3. $\mathrm{n}=4, \mathrm{l}=1, {\mathrm{m}}_{\mathrm{l}}=0, {\mathrm{m}}_{\mathrm{s}}=+1/2$
4. $\mathrm{n}=3, \mathrm{l}=2, {\mathrm{m}}_{\mathrm{l}}=–2, {\mathrm{m}}_{\mathrm{s}}=–1/2$
5. $\mathrm{n}=3, \mathrm{l}=1, {\mathrm{m}}_{\mathrm{l}}=–1, {\mathrm{m}}_{\mathrm{s}}=+1/2$
6. $\mathrm{n}=4, \mathrm{l}=1, {\mathrm{m}}_{\mathrm{l}}=0, {\mathrm{m}}_{\mathrm{s}}=+1/2$

 Indicate the number of unpaired electrons in: (a) $\mathrm{P}$, (b) $\mathrm{Si}$, (c) $\mathrm{Cr}$, (d) $\mathrm{Fe}$, (e) and $\mathrm{Kr}$.