Lime types — The lime that is mainly calcium oxide and vigorously slakes with water is called

Introduction / Context:
Lime classification matters for mortar behavior, setting mechanisms, and durability. Recognizing which form of lime reacts vigorously with water helps ensure correct handling and safety at site.

Given Data / Assumptions:

• The material in question is predominantly CaO.
• It reacts exothermically with water to form Ca(OH)2.

Concept / Approach:
Quick lime is calcium oxide produced by calcining limestone. On contact with water it undergoes slaking, generating heat and expanding as it converts to calcium hydroxide (fat lime), which is later used in mortars.

Step-by-Step Solution:
Identify composition: mainly CaO.Identify reaction: CaO + H2O → Ca(OH)2 with heat evolution.Therefore, the correct term is quick lime.

Verification / Alternative check:
Material safety sheets for quick lime warn of heat on hydration; this matches vigorous slaking behavior.

Why Other Options Are Wrong:
Fat lime: already hydrated Ca(OH)2; does not slake further.Hydraulic / Poor / Dolomitic lime: compositions and reactions differ; not primarily CaO with vigorous slaking.

Common Pitfalls:
Using quick lime directly in mortars without proper slaking can cause later expansion and cracking.

Final Answer:
Quick lime (calcium oxide)