Questions

The oceanic crust mainly consists of silica and __________.

Which of the following is a greenhouse gas or a gas which can deplete the ozone layer?

In the following question, out of the four alternatives, select the alternative which is the best substitute of the words/sentence.

Have saliva dripping copiously from the mouth

In the following question, out of the four alternatives, select the alternative which is the best substitute of the words/sentence.

Search for and collect anything usable from discarded waste

In the following question, out of the four alternatives, select the alternative which best expresses the meaning of the idiom/phrase.
Damp squib

In the following question, out of the given four alternatives, select the one which best expresses the meaning of the given word.

Allay

Select the odd word from the given alternatives.

Improve the bracketed part of the sentence.
Would it be impolite (to be asked) why they are leaving?