0 the change in coordination number of silicon (si) when o-quartz transforms to stishovite, which has octahedral coordination, is (b) 4 (a) 2 (c) 6 (d) 8

how do you know it's surrounded by 6

should i consider 2 as correct answer?

Correct answer would be 2... As the coordination number of stishovite is 6 while that of alpha quartz(or other quartz polymorph) is 4. So difference (6-4=2) ...

The coordination number of stishovite is 6, so the silicon atoms are all surrounded by 6 oxygen atoms. The crystal structure of stishovite does not fit in the classification scheme...