The ideal fuel for Class 8 science is a fuel that is cheap, easily available, easy to store and transport, has a high calorific value, and burns cleanly without polluting much. Common examples are LPG , CNG, and natural gas.

Class 8 meaning

In Class 8 science, “ideal fuel” usually means a fuel with the best practical properties for daily use. It should give a lot of heat, burn at a moderate rate, and be safe to use.

Main qualities

  • Low cost.
  • Readily available.
  • Easy to transport and store.
  • High calorific value.
  • Burns at a moderate rate.
  • Produces little smoke or harmful gases.

Examples

Fuel| Why it is suitable
---|---
LPG| High calorific value, burns cleanly, easy to use. 13
CNG| Cleaner than many solid fuels and commonly used. 31
Natural gas| Clean-burning and efficient. 13

One-line answer

So, the ideal fuel for Class 8 is usually described as a fuel like LPG or CNG because it is efficient, convenient, and causes less pollution.

TL;DR: An ideal fuel should be cheap, available, safe, high in calorific value, and low in pollution; LPG and CNG are standard examples.