Scientist of UK have invented the cars working on hydrogen fuel cells instead of petrol engines

Scientist of UK have invented the cars working on hydrogen fuel cells instead of petrol engines. Here hydrogen is used as a sources of electrical energy i.e., a reaction of hydrogen and oxygen if used to generate electrical energy. It has many advantages over the conventional fossil fuels and electric power generation.
(i) Give two advantages of hydrogen over fossil fuels?
(ii) What is the efficiency of fuel cell as comparison to other conventional fuels?
(iii) What are the values possessed by scientists of UK?

(i) It produce more energy per unit mass of fuel and does not create pollution.
(i) The efficiency of fuel cells is 70% whereas other conventional cells are only 40% efficient.
(iii) The values possessed by UK scientists are control of environmental pollution and generation of new sources of energy which are highly efficient.