If there is no greenhouse effect , then the average temperature of the earth will be
(a) `-18^@C`
(b) `0^@C`
(c) `-10^@C`
(d) `15^@C`

Options

A. `-18^@C`
B. `0^@`
C. `-10^@C`
D. `15^@C`

Answer

To solve the question regarding the average temperature of the Earth if there were no greenhouse effect, we can follow these steps:

### Step 1: Understand the Greenhouse Effect
The greenhouse effect is a natural process where certain gases in the Earth's atmosphere, known as greenhouse gases (like carbon dioxide, methane, and water vapor), trap heat from the sun. This process helps to maintain the Earth's temperature at a level that can support life.

### Step 2: Consider the Absence of the Greenhouse Effect
If there were no greenhouse gases, the heat from the sun would not be trapped in the atmosphere. Instead, most of it would be reflected back into space. This would lead to a significant drop in the Earth's average temperature.

### Step 3: Determine the Average Temperature Without the Greenhouse Effect
Scientific estimates suggest that without the greenhouse effect, the average temperature of the Earth would be around -18°C. This is significantly lower than the current average temperature, which is approximately 15°C due to the greenhouse effect.

### Step 4: Analyze the Options
Given the options:
- (a) -18°C
- (b) 0°C
- (c) -10°C
- (d) 15°C

The only option that corresponds to the estimated average temperature of the Earth without the greenhouse effect is (a) -18°C.

### Conclusion
Therefore, the answer to the question is (a) -18°C.

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