Which one of the following gases, released from bio-gas plant is used as a fuel gas?

Which of the following is the procedure for a biogas plant?

Which one of the following is used as an explosive?

To avoid ‘knocking’ of the engine of a car, which one of the following is used as an anti-knocking agent?

Which one of the following has the highest fuel value?

Which among the following is the main constituent of biogas?