Which statements are true for Quartz (a silicate-based mineral)?
I. Its chemical formula is SiO2.
II. Its hardness on the Mohs scale is 7.
III. Insoluble in hydrofluoric acid.
IV. Specific gravity is 2.6 - 2.65.
1
I and II
2
I, II and III
3
I, II and IV
4
All are true.