$(i)$ Write the value of the solar constant of the Sun.
$(ii)$ What type of mirror is used in a box-type solar cooker?
$(iii)$ Why is it difficult to use hydrogen as a source of energy?
$(iv)$ What is the maximum temperature attained in a concave reflector-type solar cooker?
$(v)$ Fossil fuels are classified as a non-renewable source of energy. Explain why.

(N/A) $(i)$ The solar constant is approximately $1.4 \, kW/m^2$.
$(ii)$ $A$ plane mirror is used in a box-type solar cooker to reflect sunlight into the box.
$(iii)$ Hydrogen is difficult to use as a source of energy because: $(i)$ it is highly combustible and burns with an explosion,and $(ii)$ it has a very low ignition temperature,making it dangerous to store and transport.
$(iv)$ $A$ concave reflector-type solar cooker can attain temperatures up to about $200^{\circ}C$.
$(v)$ Fossil fuels are classified as non-renewable because they take millions of years to form and cannot be replenished once they are consumed.