Well, an alpha particle is made up of four subatomic particles: two protons, and two neutrons. Helium has two protons and two neutrons, meaning that alpha particles are, in fact, similar to helium nuclei. That's why they are written as 2^4 He
Answer:
So the molar mass of C4,H10 is
58.12g mole -1
solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 

Dipole-dipole interactions, and London dispersion interactions