Questions

2016 Australian Open –Men's Singles. Novak Djokovic was the defending champion and successfully defended his title, defeating Andy Murray, 6–1, 7–5, 7–6 in arematch of the previous year's final, and the fourth Australian Open final between the pair.

20 August, the birth anniversary of Rajiv Gandhi, which is celebrated as Sadbhavna Diwas (Harmony Day). Sadbhavana Diwas commemorates the memory of our late erstwhile Prime Minister, Rajiv Gandhi.

Burning gasoline is the only process that involving in a chemical change in the given options. A chemical change is a change in the starting substances that are called reactants from the formed new substances that are called products. 

The given sentence is in simple present tense and states a general fact, hence the latter half of the sentence with the blank will also be in the simple present tense. Since the subject in the latter part of the sentence is singular .i.e. 'the number', the verb will be followed accordingly. Hence, option 4 is the correct answer.