When electricity is passed through calcium nitrate solution in water, ______ is formed at the cathode because it requires ________ electrical energy to get discharged.

Options

A. Hydrogen, more
B. Calcium more
C. Hydrogen, less
D. Calcium, less

Answer

To solve the question, we need to analyze the electrolysis of calcium nitrate solution (Ca(NO3)2) and determine what is formed at the cathode and the energy requirements for that reaction.

### Step-by-Step Solution:

1. **Identify the Components in the Solution**:
- Calcium nitrate dissociates in water to form calcium ions (Ca²⁺) and nitrate ions (NO3⁻).
- The solution also contains water, which can dissociate into hydrogen ions (H⁺) and hydroxide ions (OH⁻).

2. **Determine the Reactions at the Electrodes**:
- At the cathode (negative electrode), reduction occurs. This means that cations (positively charged ions) will be attracted to the cathode.
- The two main cations present are Ca²⁺ and H⁺ from water.

3. **Evaluate the Discharge of Ions**:
- The discharge of ions at the cathode depends on their standard electrode potentials.
- Calcium ions (Ca²⁺) can be reduced to calcium metal (Ca), but this reaction requires a higher amount of electrical energy.
- Hydrogen ions (H⁺) can be reduced to form hydrogen gas (H₂), which requires less electrical energy.

4. **Identify the Product at the Cathode**:
- Since hydrogen ions require less energy to be discharged compared to calcium ions, hydrogen gas (H₂) will be formed at the cathode.

5. **Complete the Sentence**:
- Therefore, when electricity is passed through calcium nitrate solution in water, **hydrogen gas** is formed at the cathode because it requires **less** electrical energy to get discharged.

### Final Answer:
When electricity is passed through calcium nitrate solution in water, **hydrogen gas** is formed at the cathode because it requires **less** electrical energy to get discharged.