Question

18-carat gold contains?
(A) 18% gold
(B) 24% gold
(C) 75% gold
(D) 60% gold

Answer 1

Hint: Pure gold is 24 carat and has 99.99% gold. Just cross-multiply and calculate how much percentage of gold is present in 18carat gold to get the answer.

Complete step by step solution:
- A carat is the measure used to indicate the fineness of gold or purity of gold in a gold alloy.
- The purest form of gold is 24 carat gold having 99.99% of gold.
- 24 carat gold indicates there are 24 out of 24 parts of gold.
- But pure gold is very soft, so to increase its tensile strength some other metals like copper, zinc, silver, nickel, etc.
- 18 carat gold indicates there are 18 out of 24 parts of gold and the rest 6 parts are made of other metals added to increase the strength of the ornament.
- We need to find a percentage of gold in 18 carat gold.
- 24 carat gold = 99.99%
- 18 carat gold = ?
- Therefore, 18 carat gold contains $\dfrac{18\times 99.99}{24}=74.99\text{ }\!\!%\!\!\text{ }$
- Therefore, 18 carat gold contains approximately 75% gold.

Hence, the correct answer is option (C).

Note: Remember carat, also written as karat, is the measurement unit used to determine fineness or purity of gold. Carat is also used as a measurement of weight in gemstones like diamonds. In this case, 1 carat = 0.1gram.