Plastering and Pointing MCQ with answer and solution

Concept

Barium plaster contains barium sulphate. It absorbs X-rays, so it is used as the finishing coat on walls of X-ray rooms.

Step-by-step solution

1. X-ray rooms need wall finishes that stop X-ray radiation from passing through. 2. Barium sulphate is a heavy compound that absorbs X-rays well. 3. Barium plaster is made with barium sulphate, so it gives radiation protection. 4. Answer is (C).

Explanation

Barium plaster is a special plaster made with barium sulphate. It is dense and absorbs X-rays, so it is used as the final coat in X-ray rooms of hospitals. The other options are only coloured or decorative cements.

Why the other options are wrong

A: Colocrete is a coloured cement used for decorative finishes. B: Parian cement is a hard-finish gypsum-based plaster used for smooth decorative surfaces, not for radiation shielding. D: Snowcrete is a white cement used for white or decorative finishes.

Shortcut

X-ray room means barium (barium meal is also used in X-ray tests).

Common mistake

Choosing a special cement such as Snowcrete or Colocrete. These are only decorative and give no X-ray protection.