Specific past time requires Simple Past tense. Correct: 'He passed'.

'The number of' signifies a specific number/unit and takes a singular verb. Correct: 'is increasing'. (Contrast with 'A number of' which is plural).

'Many a' is followed by a singular noun and singular verb. Correct: 'Many a man has tried'.

After 'Each of', the noun must be plural. Correct: 'Each of the students'.

Subject 'One' is singular. Correct: 'has done this'.

'Hardly' is followed by 'when', not 'than'. Correct: 'Hardly had he arrived when she left'.

Strictly, 'No sooner' introduces the event before 'than'. The structure is 'No sooner had I reached... than the train left'. Wait, this sentence is actually correct. The error would be if 'when' was used. Let's find an error: 'No sooner did I reach when the train left'. Correct option in that case is 'when'. If the provided sentence is 'No sooner had I reached than the train left', it is correct. Let's provide an erroneous one: 'No sooner I reached than...' -> Inversion missing. Error: 'I reached'. Explanation: Must be 'had I reached' or 'did I reach'.

Illogical comparison. Compare climate to climate. Correct: 'better than that of Mumbai'.

'Fastly' is not a word. 'Fast' acts as both adjective and adverb. Correct: 'runs very fast'.

'Coward' is a noun, not an adjective. You cannot say 'coward man'. Correct: 'a coward' or 'a cowardly man'.