Teaching BPSC बिहार माध्यमिक TGT (9 to 10) शिक्षक भर्ती 4.0 Mock Test General Science Biology Ecology & Environment
The depletion in atmospheric ozone layer in last century was due to:
1
chlorofluorocarbon
2
carbon monoxide
3
methane
4
More than one of the above
5
None of the above