What is the answer for those 2 questions? Help me please

Which of these reactions are redox reactions? check all that apply.cd + hcl → cdcl2  + h2cucl2  + na2s → 2nacl + cuscaco3  → cao + co2          2zns + 3o2  → 2zno + 2so2          ch4  + 2o2  → co2  + 2h2o

What problem would a person have if the nucleic acid in one of his or her cells were damaged?

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million