The lime which contains mainly calcium oxide and slacks with water is
- Afat lime
- Bquick limeCorrect
- Chydraulic lime
- Dpoor lime
Solution
Concept
Classification and properties of quick lime
Formula
NONE
Step-by-step solution
1. Calcination of limestone yields calcium oxide (CaO), which is commercially known as quick lime. 2. Quick lime reacts vigorously with water in a process called slaking to form calcium hydroxide. 3. Therefore, the lime containing mainly calcium oxide and slacking with water is quick lime. Answer: B
Explanation
Quick lime is produced by calcining limestone and consists primarily of unslaked calcium oxide. When water is added to quick lime, it undergoes an exothermic reaction called slaking to form calcium hydroxide. Fat lime is a type of slaked lime, but the direct product consisting mainly of calcium oxide that slacks with water is quick lime.
Why the other options are wrong
A) Fat lime contains high calcium oxide and slakes vigorously to form a soft putty. C) Hydraulic lime contains silica and alumina, enabling it to set underwater. D) Poor lime contains more than 30% clay impurities and slakes very slowly.
Shortcut
Quick lime is pure calcium oxide (CaO) before slaking with water.
Common mistake
Confusing quick lime (calcium oxide) with fat lime or slaked lime (calcium hydroxide).
Correct answer: B) quick lime