Most of earths atmosphere is the gas nitrogen n2molecules

Question

Solve the all given parts of following question:

Question: Most of earth's atmosphere is the gas nitrogen (N2molecules). The coldest natural temperature ever observed on earth was -129 °C, while the warmest was 58 °C.

Part A: What is the molecular mass, in kilograms, of the N2gas? Remember that N has a mass of 14 u, so N2has a mass of 28 u?

Part B: What is the root-mean-square speed in m/s of the nitrogen molecules at a temperature of -129 °C?

Part C: What is the root-mean-square speed in m/s of the nitrogen molecules at a temperature of 58 °C?

Part D: Convert the answers for parts B and C to miles per hour.

I am having a hard time understanding these questions. So if you answer please explain how you found the answers.