Question

What is mixed with sand and water to make mortar which is used in construction of buildings?
A. $ NaoH $
B. $ KOH $
C. $ N{H_4}OH $
D. $ Ca{\left( {OH} \right)_2} $

Answer 1

Hint: Before we get into the question, let's talk about mortar. Mortar, which is an intimate mixture of inert cementing materials like clay, lime, cement, or a combination of these, and fine aggregates like sand and water, is typically used for plastering the masonry surface.

Complete answer:
Mortar is a paste made up of sand, a binder like cement or lime, and water that is applied as a paste and hardens.
 Hydrated lime is another name for calcium hydroxide. It is a colourless, dry crystalline powder made by combining calcium oxide (quicklime) with water in a method known as "slaking." Hydrated lime, also known as slack lime, builders lime, or pickling lime, is used to make mortars, plasters, cements, paints, hard rubber goods, petrochemicals, and leather tanning.
For over 2000 years, lime has been an essential component of mortars. The properties of hydrated lime give cement-lime mortars a distinct advantage over other masonry mortar materials in masonry applications. Lime has a high water retention rate, allowing cementitious materials to cure as quickly as possible. High initial flow allows for quick coverage of all masonry units. Cement-lime mortar has a low air content, which improves bond strength.
Hence, from the above gathered information we can conclude that calcium hydroxide $ Ca{\left( {OH} \right)_2} $ is mixed with sand and water to make mortar which is used in construction of buildings.
So, the correct option is: (D) $ Ca{\left( {OH} \right)_2} $ .

Note:
However, the most common use of hydrated lime is in the steel industry, where it is used to remove impurities. Other metals are often made with hydrated lime. Soil stabilisation for roads, earthen dams, airfields, and building foundations is the most common use of hydrated lime in construction. Acidic soils may benefit from the use of hydrated lime to increase the pH. This is also known as "sweetening" the soil.