Lens of spectacles are made from |
|||||||
(a) |
soft glass |
(b) |
hard glass |
(c) |
pyrex glass |
(d) |
flint glass |
Lens of spectacles are made from |
|||||||
(a) |
soft glass |
(b) |
hard glass |
(c) |
pyrex glass |
(d) |
flint glass |