Answer:
a) Watch the attaccment
b) Ethyl bromide is more reactive than n-propyl bromid, and this more than neopentyl bromide. Ethyl bromide has less steric hindrance than the others, to SN2 reactions.
c) t-butyl bromide is more reactive than isopropyl bromide, and this more than ethyl bromide. t-butyl bromide structure stabilize the carbocation, better than the others.
Explanation:
Speed of SN2 reactions depends on steric hindrance, the less hindrance, the most reaction speed, meaning more reactivity. Then, those linear structures are more reactive to SN2 reactions.
In the other hand, speed of SN1 reactions depends on the stability of the carbocation formed. Structure with ramifications can stabilize better the carbocation, these structures are more reactive to SN1 reactions.
Can’t help you man, sorry
The type of molecule that is shown is D. Alcohol
Answer: 
Explanation: A double displacement reaction is one in which exchange of ions take place.
The compounds which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Thus the exchange of ions take place and all the compounds are soluble so the chemical formulas are followed by the symbol (aq).
