When a cleaned strip of zinc metal is placed in a solution of `CuSO_(4)`, a spontaneous reaction occurs, which of the following observation(s) is/are made?

Options

A. The mass of zinc metal decreases gradually
B. The copper metal start depositing on either zinc plate or settles down the vessel
C. The solution remains electrically neutral
D. The temperature of the solution decreases as it is an endothermic reaction.

Answer

To solve the question regarding the observations made when a cleaned strip of zinc metal is placed in a solution of copper sulfate (CuSO₄), we can analyze the chemical reaction and its implications step by step.

### Step-by-Step Solution:

1. **Identify the Reaction**:
When zinc (Zn) is placed in a copper sulfate solution, a displacement reaction occurs. The zinc displaces copper from the copper sulfate solution because zinc is more reactive than copper.

**Chemical Equation**:
\[ \text{Zn (s)} + \text{CuSO}_4 (aq) \rightarrow \text{ZnSO}_4 (aq) + \text{Cu (s)} \]

2. **Observation of Mass Change**:
As the reaction proceeds, zinc metal is oxidized to zinc ions (Zn²⁺), which means that the mass of the zinc strip will decrease over time. This is because zinc is losing mass as it transforms into zinc ions.

**Observation**: The mass of zinc metal decreases gradually.

3. **Deposition of Copper**:
The copper ions (Cu²⁺) from the copper sulfate solution are reduced to solid copper (Cu) and will start depositing either on the zinc strip or settle down in the vessel.

**Observation**: Copper metal starts depositing on the zinc plate or settles down in the vessel.

4. **Electrical Neutrality**:
Initially, the copper ions in the solution are positively charged (Cu²⁺). When zinc is oxidized, it releases two electrons, and the copper ions gain these electrons to become neutral copper atoms. The overall charge balance is maintained, meaning the solution remains electrically neutral.

**Observation**: The solution remains electrically neutral.

5. **Temperature Change**:
The reaction between zinc and copper sulfate is exothermic, meaning it releases heat rather than absorbing it. Therefore, the temperature of the solution will increase rather than decrease.

**Observation**: The temperature of the solution does not decrease; this statement is incorrect.

### Summary of Observations:
- The mass of zinc metal decreases gradually. (Correct)
- Copper metal starts depositing on the zinc plate or settles down in the vessel. (Correct)
- The solution remains electrically neutral. (Correct)
- The temperature of the solution decreases as it is an endothermic reaction. (Incorrect)

### Final Conclusion:
The correct observations are:
1. The mass of zinc metal decreases gradually.
2. Copper metal starts depositing on the zinc plate or settles down in the vessel.
3. The solution remains electrically neutral.