The greatest air pollution disaster of the last few decades was observed in

Which of the following is a pollution-related disorder?

In water bodies,fish die due to eutrophication because of the lack of which of the following?

The cause of decline in the population of reptiles and birds is

Delhi is one of the most polluted cities of the world. Which of the following steps were taken by the government to reduce vehicular pollution in Delhi?
$I.$ Phasing out of old vehicles
$II.$ Use of unleaded petrol
$III.$ Use of low sulphur petrol and diesel
$IV.$ Use of catalytic converters in vehicles
$V.$ Applying stringent pollution level norms for vehicles
$VI.$ Switch over of public transport from diesel/petrol to $CNG$
Which of the statements given above are correct?

Photochemical smog was first observed in .......... .