Asample of propane c3 h8 contains 10.0 miles of carbon atoms

We need to calculate the ratio of C to H in the molecule:
We have 3 C and 8 H, so the ratio is 3:8
If we have 10.0 moles C, we divide that by the number of C atoms to get the factor:
10/3 = 3.33
The we multiply the number of H atoms, 8, by this factor:
3.33 x 8 = 26.67
So we have 10.0 moles of C and 26.67 moles of H for a total of 36.67 moles in the sample.

No. an alpha particle is a pair of protons and a pair of neutrons, i.e. a helium

Rate law for this reaction israte of the reaction = k[a]²[b].second order in a  means concentration of a in power of two, and  first order in b means concentration of b in power of one.