Which cannot be separated into simpler substances by physical or mechanical methods such as filtering, boiling, or sifting?

Question

Which cannot be separated into simpler substances by physical or mechanical methods such as filtering, boiling, or sifting? 
A. a crystalline solid
B. a sublimation
C. a pure substance
D. an amorphous solid

I think it is A am I right?

marie · Accepted Answer

anyone?

DrBob222 · Answer

I don't think it's A.

Weather · Answer

A is incorrect. Please re-read this question carefully and when you're done, please try again.

haikyuu · Answer

what is the correct answer then?????