Answer:
A piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. Some particles had their paths bent at large angles. A few even bounced backward. The only way this would happen was if the atom had a small, heavy region of positive charge inside it.
Answer:
2Zn + 2HCl = H2 + 2ZnCl
Explanation:
Zn is a metal, when metals have reaction with strong acid it will produce H2 gas and the metal's salt which is ZnCl.
Later on you just make the equation in balance.
Answer:
Reasonable Second step- 
Explanation:
The given single step chemical reaction is as follows.

Suppose a two-step mechanism is proposed for this reaction,
The reaction occured in two steps they are as follows.

