Hey there! The answer to your first question is SILICON, Nickle has 28 protons, silicon has 14, 14+14=28. Its the only element thats adds up. I dont know about the 2nd one myself.
<Sgx,JASYLDhLAxhclsxb cddont know
Answer:
Use the Bromotriflouride catalyst, BF₃
Explanation:
The BF₃ is most likely to yield less desired side products. The effect lies in the reaction mechanism.
BF₃ is a Lewis acid. Its role is to promote the ionization of the HF. This is achieved through the electrophilic mechanism. The reaction mechanism is as follows:
2 - methylpropene + H-F-BF₃ → H-F + H₃C + benzene
butylbenzene + F-BF₃ → tert-butylbenzene + H-F + BF₃ (regenerated catalyst)