Q447
In shallow mines, to prevent breathing of air to the depillared area through cracks on surface, the cracks are blanketted with a layer of sand nearly . . . . . . . . meters thick.
A.
1 m
B.
1.8 m
C.
2 m
D.
1.2 m
AnswerAnswer: Option D
Solution
Answer: Option D
No explanation is given for this question Let's Discuss on Board