Which of the following is incorrect w.r.t. Controlled apparatus of Miller and Urey experiment?

Options

A. `800^@`
B. Electric sparks of 75,000 volt
C. `CH_4 : NH_3 : H_2 = 2 : 2 : 1`
D. Devoid of energy source

Answer

To solve the question regarding the incorrect statement about the controlled apparatus of the Miller and Urey experiment, we can follow these steps:

### Step 1: Understand the Miller and Urey Experiment
The Miller and Urey experiment, conducted in 1952, aimed to simulate the conditions of early Earth to test the hypothesis of abiogenesis, which is the idea that organic compounds could arise from inorganic precursors.

### Step 2: Identify the Components of the Experiment
The experiment involved a closed apparatus where a mixture of gases representing the early Earth's atmosphere (methane, ammonia, hydrogen, and nitrogen) was used. Electric sparks were introduced to simulate lightning, which was believed to be a source of energy on early Earth.

### Step 3: Analyze the Given Options
1. **800 degrees Celsius**: This is a high temperature, but it was indeed one of the conditions used in the experiment.
2. **Electric sparks of 75,000 volts**: This was the voltage used to simulate lightning, and it is accurate.
3. **Mixture of gaseous substances**: The experiment used a specific ratio of gases, which is crucial to determine if this statement is correct or incorrect.
4. **Devoid of energy source**: This statement is incorrect because the experiment used electric sparks as an energy source.

### Step 4: Evaluate the Gaseous Mixture Ratio
The correct ratio of gases used in the experiment was not clearly stated in the options. The correct ratio was approximately 2 parts hydrogen, 1 part methane, and 2 parts ammonia (H2:CH4:N2). If the options suggest a different ratio, that would be the incorrect statement.

### Conclusion
After analyzing all the options, the incorrect statement regarding the controlled apparatus of the Miller and Urey experiment is the one that misrepresents the ratio of the gaseous mixture or states that it is devoid of an energy source.

### Final Answer
The incorrect statement is that the apparatus is devoid of an energy source.

---