Chemical Equations

To solve this question, we need to identify the chemical formula of the blue-colored copper sulfate crystal.

1. Understanding Copper Sulfate Crystals:
- Copper sulfate (CuSO₄) can form hydrated crystals, which are blue in color. The blue color is due to the presence of water molecules in the crystal structure.

2. Identifying the Correct Hydrate:
- The blue-colored copper sulfate crystals are typically in the form of CuSO₄·5H₂O, known as copper sulfate pentahydrate.

3. Analyzing the Options:
- Option (A) CuSO₄·H₂O: This represents copper sulfate monohydrate, which is not blue in color.
- Option (B) CuSO₄·2H₂O: Represents copper sulfate dihydrate, which is not blue.
- Option (C) CuSO₄·5H₂O: This is the correct formula for blue copper sulfate crystals (copper sulfate pentahydrate).
- Option (D) CuSO₄·10H₂O: This is not correct for the blue-colored copper sulfate.

Final Answer:
Option (C) CuSO₄·5H₂O is correct.

To solve the problem, we need to balance the chemical equation and find the values of A, B, C, and D in the equation:

1. Given Equation:
The unbalanced chemical equation is:

2. Balancing the Equation:
Let's balance the atoms on both sides of the equation:

Na: There is 1 Na on the left side (from Na) and 1 Na on the right side (from NaOH), so and .
H: There are 2 H atoms from water (H2O) on the left side and 2 H atoms in NaOH and 2 H atoms in H2 on the right side. So, and .
O: There is 1 O atom in NaOH on the right side, which balances the 1 O atom in H2O on the left side. Thus, and .

3. Final Balanced Equation:
The balanced equation is:

Final Answer:
The values of A, B, C, and D are .

To solve the problem, we need to identify the compound formed when excess is passed through lime water.

1. Understanding the Reaction:
Lime water is a solution of calcium hydroxide in water. When excess carbon dioxide ( ) is passed through lime water, the following reactions occur:

• First, calcium hydroxide reacts with carbon dioxide to form calcium carbonate:
• If excess is passed, the calcium carbonate reacts further with to form calcium bicarbonate:

2. Conclusion:
When excess is passed through lime water, the compound formed is calcium bicarbonate .

Final Answer:
The correct answer is (D) .