41) For railway ballast, the stone should be

• (a) soft with a uniform texture
• (b) hard, heavy, strong and durable
• (c) hard, tough, resistant to abrasion and durable
• (d) hard, dense, durable, tough and easily workable

42) The quarrying of stone by the method of wedging is successfully carried out in

• (a) sandstones
• (b) limestones
• (c) marbles
• (d) all of these

43) When quarrying is to be done in hard stone and compact rocks, the usual method of quarrying is

• (a) by wedging
• (b) by channelling machine
• (c) by blasting
• (d) all of the above

44) The compressive strength of felspar is ................. quartz.

• (a) equal to
• (b) less than
• (c) more than

45) The most powerful explosive used in blasting is

• (a) blasting power
• (b) dynamite
• (c) gun cotton
• (d) cordite