CBSE 2023 · Region 1 · Set 1 · Q30 · 3 marks
Draw the energy level diagram for hydrogen atom. Mark the transitions corresponding to the series lying in the ultraviolet region, visible region and infrared region.Draw a diagram to show the variation of binding energy per nucleon with mass number for different nuclei and mention its two features. Why do lighter nuclei usually undergo nuclear fusion?
Draw the energy level diagram for hydrogen atom. Mark the transitions corresponding to the series lying in the ultraviolet region, visible region and infrared region.
Draw a diagram to show the variation of binding energy per nucleon with mass number for different nuclei and mention its two features. Why do lighter nuclei usually undergo nuclear fusion?
Marking-scheme solution
Energy level diagram for hydrogen atom \(\displaystyle 1 \frac{1}{2}\) Transitions corresponding to ultraviolet region, visible region and infrared region \(\displaystyle \frac{1}{2}+\frac{1}{2}+\frac{1}{2}\)
Features of diagram
1. Binding energy per nucleon is practically independent of atomic number for nuclei of middle mass number ( \(\displaystyle 30<\mathrm{A}<170\) )
2. The curve has maximum of about $\displaystyle 8.75$ MeV for \(\displaystyle \mathrm{A}=56\) and has a value of $\displaystyle 7.6$ MeV for \(\displaystyle \mathrm{A}=238\)
3. Binding energy per nucleon is lower for both light nuclei ( \(\displaystyle \mathrm{A}<30\) ) and heavy nuclei \(\displaystyle (\mathrm{A}>170)\)
Two lighter nuclei fuse together to form heavier nuclei as the binding energy per nucleon of fused heavier nuclei is more than the binding energy per nucleon of the lighter nuclei. Thus the final system is more tightly bound
AtomsThe Line Spectra of the Hydrogen AtomApplyshort_answermedium
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