Correct Answer: B
Explanation:
Sol.
It is an extension of the older carat system of denoting the purity of gold by fractions of 24, such as ’18 carat’ for an alloy with 75% (18 parts per 24) pure gold by mass. Because of the softness of pure (24 carat gold,) it is usually alloyed with base metals for use in jewellery, altering its hardness and ductility, melting point, colour and other properties.