What does soporific mean?

[Thameem]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #75 "At the End of the Day (4)", question 6

Well, I don't know about you but all this is having a very soporific ......... on me

(a) effect
(b) affect
(c) affection
(d) affectation

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #75 "At the End of the Day (4)", answer 6

Well, I don't know about you but all this is having a very soporific effect on me

Correct answer: (a) effect

Your answer was: incorrect
Well, I don't know about you but all this is having a very soporific affection on me
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Please explain what is soporific? because of this word I answered the question wrongly. I am very poor in vocabulary. Please tell me how to improve the vocabulary because of that I am getting confused with phrases. Your explation will be highly appreciated. Thanks

[Mister Micawber]

'Soporific' would not affect your choice; it is irrelevant. Try the question with this sentence:

Well, I don't know about you, but all this is having a very bad ......... on me.
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Native English teacher at Mister Micawber's