Answer:
The answer to your question is: B. Nickel Sulfate
Explanation:
A. Nickel sulfur oxide this compound do not exist, this option is incorrect.
B. Nickel sulfate This compund exist and the formula is NiSO₄
C. Nickel oxygen sulfide This compound do not exist, the order of the names is inocrrect.
D. None of these This option is incorrect because because letter B is correct.
System to surroundings since energy is released in an exothermic reaction
Answer:
The balanced double displacement reaction is as follows.

Explanation:
The given reactant has sodium,chloride and copper sulfate ions.
In the double displacement reaction, two ionic compounds exchange their cations.
Sulphate and chloride ions are cations these are exchanged sodium and copper elements.
Hence, the balanced double exchange reaction is as follows.

Physical changes occur when substances are mixed but don't chemically react.