NDA 2 2025 GAT, question 99

Topic: Chemistry

Q99

Which one of the following is NOT present in cement ?

(a) $2CaO\cdot SiO_{2}$
(b) $3CaO\cdot SiO_{2}$
(c) $4CaO\cdot SiO_{2}$ Correct answer
(d) $3CaO\cdot Al_{2}O_{3}$

Solution.

Answer: (c) $4CaO\cdot SiO_{2}$

The principal cement compounds include dicalcium silicate (2CaO·SiO₂), tricalcium silicate (3CaO·SiO₂) and tricalcium aluminate (3CaO·Al₂O₃).
The listed 4CaO·SiO₂ is not one of these standard constituents; do not confuse it with tetracalcium aluminoferrite.