71) Efflorescence is caused if

• (a) the alkaline salt is present in the bricks
• (b) the clay used for making bricks contain pyrite
• (c) the water used for pugging the clay contains gypsum
• (d) all of the above

72) The good clay for making bricks is

• (a) unweathered clay
• (b) weathered clay
• (c) silted soil
• (d) black cotton soil

73) The process of mixing clay, water and other ingredients to make bricks, is known as

• (a) tempering
• (b) pugging
• (c) kneading
• (d) moulding

74) The hand made bricks are ........... to machine made bricks for facing purposes.

• (a) superior
• (b) inferior

75) The bricks after moulding should be dried in

• (a) open air
• (b) sun for 3 to 8 days
• (c) air for 3 to 8 days but not in sun
• (d) hot air for 3 days