The correct sequence of number of carbon atoms present in (a) compressed natural gas, (b) diesel and (c) petrol is :

Question

Accepted Answer

The correct sequence of the number of carbon atoms present in (a) compressed natural gas, (b) diesel, and (c) petrol is given as Option 2: b > c > a. Let's provide a detailed explanation to justify why this option is correct and why the other options are incorrect.

1. **Explanation for Option 2 (Correct Answer: b > c > a):**

- **Diesel (b):** Diesel is a complex mixture of hydrocarbons, primarily consisting of alkanes with carbon chain lengths ranging from approximately C10 to C22. This means diesel has a relatively high number of carbon atoms compared to other fuels.
   
   - **Petrol (c):** Petrol, also known as gasoline, typically contains hydrocarbons with carbon chain lengths ranging from C4 to C12. This places petrol in the middle range in terms of the number of carbon atoms.
   
   - **Compressed Natural Gas (a):** Compressed natural gas (CNG) primarily consists of methane, which has only one carbon atom (CH4). Therefore, CNG has the lowest number of carbon atoms among the three.

Based on the above information, the sequence b > c > a is correct because diesel has the highest number of carbon atoms, followed by petrol, and then compressed natural gas.

2. **Explanation for why the other options are incorrect:**

- **Option 1 (a > b > c):** This option suggests that compressed natural gas has more carbon atoms than diesel and petrol, which is incorrect. CNG primarily consists of methane with only one carbon atom, making it the lowest in carbon content.
   
   - **Option 3 (c > a > b):** This option suggests that petrol has more carbon atoms than compressed natural gas and diesel, which is incorrect. While petrol has more carbon atoms than CNG, it has fewer than diesel.
   
   - **Option 4 (a > c > b):** This option suggests that compressed natural gas has more carbon atoms than petrol and diesel, which is incorrect. As previously mentioned, CNG has the least number of carbon atoms.

In conclusion, Option 2 (b > c > a) is the correct answer because it accurately reflects the order of the number of carbon atoms present in diesel, petrol, and compressed natural gas, respectively.