The correct statements among (a) to (d ) regarding `H_(2)` as a fuel are :
(a) It Produces less pollutants than petrol. ( b) A cylinder if compressed dihydrogen weight `~ 30 `times more than a petrol tank producing the same amount
( c ) Dihydrogen is stored in tanks of metal alloys like `NaNi_(5)`
( D) On combusion ,values of energy released per gram of liqiud dihydrogen and LPG are 50 and 142 kJ respectively

Options

A. (2), (3) and (4) only
B. (1), (2) and (3) only
C. (2) and (4) only
D. (1) and (3) only

Answer

To solve the question regarding the correct statements about H₂ as a fuel, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (a):** "It produces less pollutants than petrol."
- **Analysis:** Hydrogen (H₂) is known as a zero-emission fuel. When it combusts, it primarily produces water vapor, unlike petrol, which produces carbon dioxide (CO₂), nitrogen oxides (NOx), and other pollutants. Therefore, this statement is **true**.

2. **Statement (b):** "A cylinder of compressed dihydrogen weighs ~30 times more than a petrol tank producing the same amount."
- **Analysis:** Hydrogen has a high calorific value, but it is also less dense than petrol. To store the same amount of energy, the weight of the hydrogen storage system (including the tank) can indeed be significantly more than that of petrol. This statement is also **true**.

3. **Statement (c):** "Dihydrogen is stored in tanks of metal alloys like NaNi₅."
- **Analysis:** Hydrogen is often stored in metal hydride tanks, and NaNi₅ (sodium nickel alloy) is one of the materials used for this purpose. Thus, this statement is **true**.

4. **Statement (d):** "On combustion, values of energy released per gram of liquid dihydrogen and LPG are 50 and 142 kJ respectively."
- **Analysis:** The energy released per gram of liquid hydrogen is approximately 120-142 kJ, while LPG (Liquefied Petroleum Gas) releases about 50-55 kJ per gram. Therefore, this statement is **false** because it inaccurately states the energy values.

### Conclusion:
The correct statements regarding H₂ as a fuel are (a), (b), and (c). Thus, the answer is that statements 1, 2, and 3 are correct.