Gaseous fuels due to their advantages over ther types of fuels are becoming highly popular . The advantages to the gaseous fuels are as follows :
a. High calorific value .
b. Do not produce smoke and do not leave ash after combustion .
c. They can flow through pipes and can be ignite at a moment's notice at any place . No special devices are required for their combustion .
i. Coal gas is a good gaseous fuel as it contains `95^5` combustible gaseous such as `H_2, CH_4, CO` etc , It is obtained buy destructive distillation of coal at ` 100^@ C` .
ii. Water gas is a mixture of ` CO` and `H_2` and is prepared by passing steam over incandescnt coke . The reaction is endothermic .
iii. Producer gas , which possesses low calorific value, so prepared by passing air over red hot coke . It contains mainly nitrogen and ` CO`
iv. Semi-water gas is a mixture of water as and producer as .
v. oil gas , which is used in labs , is obtained by cracking of kerosene . It is a mixture of hydrocarbon (saturated and unsaturated ) mainly lower hydrocarbons .
iv. `LPG`, which contains ` C_3` and ` C_4` hydrocarbon of the alkane and alkene series , supplied in cylinders for domestic uses is very popular these days .
Which gas is the essential constituent of most of the fuels ?

Options

A. `CO`
B. `O_2`
C. `CO_2`
D. `N_2`

Answer

To solve the question regarding the essential constituent of most gaseous fuels, we will follow these steps:

### Step 1: Understand the Advantages of Gaseous Fuels
Gaseous fuels are becoming popular due to several advantages:
- High calorific value (they produce a lot of heat when burned).
- They do not produce smoke or leave ash after combustion, making them environmentally friendly.
- They can flow through pipes and ignite easily without special devices.

### Step 2: Identify the Types of Gaseous Fuels Mentioned
The paragraph provides information about various gaseous fuels:
1. **Coal Gas**: Contains 95% combustible gases like H₂, CH₄, CO. Obtained from the destructive distillation of coal.
2. **Water Gas**: A mixture of CO and H₂, produced by passing steam over incandescent coke (endothermic reaction).
3. **Producer Gas**: Contains mainly nitrogen and CO, produced by passing air over red-hot coke (low calorific value).
4. **Semi-Water Gas**: A mixture of water gas and producer gas.
5. **Oil Gas**: Obtained by cracking kerosene, a mixture of lower hydrocarbons.
6. **LPG**: Contains C₃ and C₄ hydrocarbons, widely used in households.

### Step 3: Analyze the Gases Present in Each Fuel
From the descriptions:
- **Coal Gas**: Contains CO.
- **Water Gas**: Contains CO.
- **Producer Gas**: Contains CO.
- **Semi-Water Gas**: Contains CO (from water gas).
- **Oil Gas**: Does not specifically mention CO but is a mixture of hydrocarbons.
- **LPG**: Does not specifically mention CO but is a mixture of hydrocarbons.

### Step 4: Determine the Common Gas
Looking through the list, carbon monoxide (CO) appears as a common component in coal gas, water gas, and producer gas. It is a significant constituent of many gaseous fuels.

### Conclusion
The essential constituent of most gaseous fuels is **carbon monoxide (CO)**.

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