Why is CNG better than diesel?

The supreme court ordered the Delhi Government to take measures to switch over all the public transport to CNG operated. Why is it preferred to diesel or petrol?

Why is it better to use a divider,than a ruler,while measuring the length of a line segment?

Why is crystallisation better than simple distillation ?

Why hot soup tastes better than cold soup?

Why the detergents with straight hydrocarbon groups are better than the detergents with branched chain hydrocarbon groups ?

" Prevention is better than Cure" Comment.