some collocations and synonymous that confused me
1.What's the difference between "consequence", "ramification" and "repercussions"?
I think "consequence" is kind of a neutral noun that stands for a result or a aftermath, and "repercussions" , i guess, are normally put in a bad situation, like if you provoke or trigger something aggressive ( revolt or coup etc.), then they are "repercussions".
And in what scenario should i use the word "ramification"?

2. How to use the word "perpetrate"?
I looked up some common collocations like "perpetrate crime", "perpetrate violence" and "perpetrate atrocity".
Can i also say "perpetrate arson" , "perpetrate vandalism", "perpetrate e-fraud" , if i'd like to put some specific crime in sentence?

3.How to use the word "instigate"?
Does it mean "start"? For instant: Given the rumor that Mayer was bribed, the ethic division instigated a investigation!

Thanks guys

Question

some collocations and synonymous that confused me
1.What's the difference between "consequence", "ramification" and "repercussions"?
I think "consequence" is kind of a neutral noun that stands for a result or a aftermath, and "repercussions" , i guess, are normally put in a bad situation, like if you provoke or trigger something aggressive  ( revolt or coup etc.), then they are "repercussions".
And in what scenario should i use the word "ramification"?

2. How to use the word "perpetrate"?
I looked up some common collocations like "perpetrate crime", "perpetrate violence" and "perpetrate atrocity".
Can i also say "perpetrate arson" , "perpetrate vandalism", "perpetrate e-fraud" , if i'd like to put some specific crime in sentence?

3.How to use the word "instigate"?
Does it mean "start"?    For instant: Given the rumor that Mayer was bribed, the ethic division instigated a investigation!

Thanks guys

Answer

That's a long question! You will probably get a better response if you only ask single questions, as they are easier to answer.
Yes, you have the right idea between consequence and repercussion. Repercussion also tends to be used more for major things, such as political decisions.
Ramifications tends to be used in a future conditional sense, e.g. if you do this, then it will have this ramification. This policy might have these ramifications.
Perpetrate isn't a common word in normal speech. It only tends to be used in a law-enforcement context, and with more general verbs like the ones you mentioned. The more specific ones sound a bit odd. 
Yes, instigate does mean start. But again, it only tends to be used in limited contexts, like discussions, investigations, riots, and rumours. I think perhaps it tends to be used in the realm of communication between people.

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