radioactivity and bohr model

1) A radioactive nuclide can decay simultaneously by two different processes which have deacy constants λ₁ and λ₂ . The effective decay constant of the nuclide is λ.

a) λ=λ₁ + λ₂

b)λ=12(λ₁ + λ₂)

c)1λ = 1λ₁ + 1λ₂

d)λ =√λ₁λ₂

2)Let the potential energy of the hydrogen atom in the ground state be zero. Then its energy in the first excited state will be

a)10.2 eV

b)13.6 eV

c)23.8 eV

d)27.2 eV

need detailed solutions plz...