(a) Topaz
(b) Corundum
(c) Quartz
(d) Apatite
Ans :- (c) Quartz
Explanation :-
The seventh minerals Moh’s hardness Quartz.
The Moh’s hardness of following minerals are :
| Minerals | Moh’s Hardness number |
| Talc | 1 |
| Gypsum | 2 |
| Calcite | 3 |
| Fluorite | 4 |
| Apatite | 5 |
| Orthoclase | 6 |
| Quartz | 7 |
| Topaz | 8 |
| Corundum, sapphire | 9 |
| Diamond | 10 |
