1) Five minutes IS enough time to complete this task. Periods of time and quantities of money are singular, so use "is" 2) Fish and chips IS my mother’s favourite dish. "fish and chips" is the name of one dish, so use a singular verb. (Some people disagree on this: https://forum.wordreference.com/threads/fish-and-chips-plural-or-singular.1342845/) 3) There’s only one bedroom, but it’s rather/quite big. Both are correct: they are both slightly weaker versions of "very." To my mind, "quite" is a little bit stronger than "rather" though. "Rather" is more common in British English.

1. is This is because it's a single chunk of time. 2. is This is because it's one dish. 3. quite I don't think that both are possible. In this context, "rather" would suggest a negative quality. For example. "Would it be possible to have another room? This one is rather small/rather dark/rather noisy". "...but it's rather big" would be what you'd say if you were highlighting a problem. For example "My car's OK but it's rather big. Maybe we should take yours? It's smaller so it'll be easier to find a parking space." In your sentence, the speaker is stressing a positive quality of the room. The guests would presumably prefer to have a room each, so the speaker is emphasising the fact that the room is big enough for two people to share. The size of the room is something positive, so 'rather' would be wrong here. NB Note about British English. The modifier 'quite' means 'fairly' i.e. not very. The room in question is not very big - it's merely big enough for two people to share ( according to the speaker, anyway).

1) Five minutes is enough time to complete this task. (you're not talking about each minute individually, but the period of time) 2) Fish and chips is my mother’s favourite dish. (you're not talking about the fish and the chips separately, but that pairing of foods) 3) There’s only one bedroom, but it’s _rather_/_ quite__ big. Both would be correct here. But I would say "..., but it's very big." or maybe "..., but it's quite large." More of a matter of custom or style.

1) Five minutes is enough time. Explanation: time is uncountable noun ( no plural ) 2) Fish and chips is ... Explanation: the one dish is called "fish and chips", as a combination of two, not separately. 3) Both options are correct. hope this helps :)

1. are because the subject is plural 2. are because the subject is plural 3.Either is correct. In the USA, they would say quite big, but in the UK they might say rather big.