quantum mechanics emission and absorption of light

please read carefully all Question posted in pictures and show me all a detailed answers for each questions so I can be able to understand how do you solve them step by step.

From this book


Thanks for your advance

Do you need a similar assignment done for you from scratch? We have qualified writers to help you. We assure you an A+ quality paper that is free from plagiarism. Order now for an Amazing Discount!
Use Discount Code "Newclient" for a 15% Discount!

NB: We do not resell papers. Upon ordering, we do an original paper exclusively for you.