Multiple choice The purity of gold is expressed in carats. The purest form of gold is ____. 25 carats 24 carats 23 carats 22 carats Reveal answer Fill a bubble to check yourself B Correct answer Explanation 24 carat gold is 99.9% pure gold. The carat system measures purity in 1/24 parts - so 24 carats means 24 out of 24 parts are pure gold. Lower carats like 22K contain other metals like copper or silver for durability.