Question

In relation to metal casting defects, match the following:

Defect	Description
P. Dross	I. Shallow blow found on a flat casting surface
Q. Scab	II. Lighter impurities appearing on the top surface of a casting
R. Scar	III. A rough, thin layer of metal, protruding above the casting surface, on top of a thin layer of sand

• A. P−II, Q−III, R−I
• B. P−II, Q−I, R−III
• C. P−III, Q−I, R−II
• D. P−III, Q−II, R−I

Hint:

Picture how each defect actually forms: floating impurities, a lifted sand flake, or a shallow surface blow.

Answer 1

The Correct Option is A

Step 1: Recall dross.
Dross is made of lighter impurities, mostly oxides, that float to the top of the poured metal and stay on the top surface once the casting solidifies.
That is description II, so P pairs with II.

Step 2: Recall scab.
A scab happens when part of the sand mold surface expands, cracks and lifts, and molten metal runs in under that lifted flake.
The result is a rough, thin metal layer sitting proud of the casting surface on top of a thin layer of sand, matching description III, so Q pairs with III.

Step 3: Recall scar.
A scar is left behind by a shallow blow defect on a flat part of the casting, matching description I, so R pairs with I.

Final Answer:
The matching is P-II, Q-III, R-I, which is option (A). \[ \boxed{P-II,\ Q-III,\ R-I} \]