The energy liberated by burning $1 \,g$ of charcoal is approximately: (in $,kJ$)

How is the slurry left over after the generation of biogas in a biogas plant used?

$(i)$ Distinguish between renewable and non-renewable sources of energy,giving one example of each.
$(ii)$ Why is the use of wood as a fuel not advised,although forests can be replenished?

Name two combustible components of biogas.

Name the process by which energy is produced in a nuclear reactor.

Aditya suggests his family to install a solar water heater at their residence. But some of the family members were in favour of installing an electric geyser.
$(a)$ Who,according to you,is taking a correct decision? Mention the value exhibited by Aditya.
$(b)$ Also,give reasons (at least $2$) for your answer.