Help in solving these questions

hope this will help you 🙏

Q2

hope this will help u😊🙏

for 4th see this video solution https://doubtnut.com/question-answer-chemistry/in-bohr-series-of-lines-of-hydrogen-spectrum-third-line-from-the-red-end-corresponds-to-which-one-of-...

Q1

just read all the formula of atomic spectra...you can able to solve all these

see this too..

check this

check this