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Q: Clay bricks are made of earth having
  • A. 35 – 70% silica and 10 -20 % alumina
  • B. 10 – 20% silica and 35 – 70% alumina
  • C. nearly equal proportion of silica and alumina
  • D. nearly equal proportions of alumina, silica and lime
Correct Answer: Option A - According to I.S. 2117–1991 the proportions of various ingredients in a good bricks earth are as follows. Silica – 50 – 60% (Major) Alumina – 20 – 30% Iron oxide – 3 – 8% Lime – 2 – 5% Na, K, Mg – 1 – 3% Alkalies – Less than 1%
A. According to I.S. 2117–1991 the proportions of various ingredients in a good bricks earth are as follows. Silica – 50 – 60% (Major) Alumina – 20 – 30% Iron oxide – 3 – 8% Lime – 2 – 5% Na, K, Mg – 1 – 3% Alkalies – Less than 1%

Explanations:

According to I.S. 2117–1991 the proportions of various ingredients in a good bricks earth are as follows. Silica – 50 – 60% (Major) Alumina – 20 – 30% Iron oxide – 3 – 8% Lime – 2 – 5% Na, K, Mg – 1 – 3% Alkalies – Less than 1%