hi! please help! i'm reviewing my answers and would like to compare! thank you!

10. 6Ni decays by a first-order process via the emission of a beta particle. The 61Ni isotope has a half-life of 100 . years. How much of the original sample of 6Ni will remain in 300 years? a. y b. 1/ c. y d. 5 e. z 11. Which of the following correctly describes R in the reaction mechanism shown? Step 1:A2+B2R+C (fast) Step 2:A2+RC (slow) a. a reactant b. an intermediate c. a catalyst d. a product e. none of the above 12. The following mechanism if proposed for the decomposition of nitrous oxide (N2O) to N2 and O2 Which rate law is consistent with the mechanism given? 2N2O=N4O2(fast)N4O22N2+O2(slow) a. Rate =k[N2O]2 b. Rate =k[N2O4] c. Rate =k[N2O] d. Rate =k[N2O4]2 e. Rate =k[N2O][N2O4]