24 - karat gold is considered to be pure gold. 18 - karat gold is considered to be about 75% gold. why is 18…

24 - karat gold is considered to be pure gold. 18 - karat gold is considered to be about 75% gold. why is 18 - karat gold considered a mixture rather than a pure substance?\na it has a variable composition of other elements and minerals.\nb its color is different than pure gold.\nc the gold atoms are not arranged in a repeating pattern.\nd it can be melted and transformed into a different substance.

24 - karat gold is considered to be pure gold. 18 - karat gold is considered to be about 75% gold. why is 18 - karat gold considered a mixture rather than a pure substance?\na it has a variable composition of other elements and minerals.\nb its color is different than pure gold.\nc the gold atoms are not arranged in a repeating pattern.\nd it can be melted and transformed into a different substance.

Answer

Brief Explanations:

A pure substance has a fixed composition. 18 - karat gold is 75% gold and the remaining 25% is made up of other elements and minerals. Its composition can vary depending on what those other substances are, which is a characteristic of a mixture. Color is not a defining factor for whether something is a pure substance or a mixture. Gold atoms in 18 - karat gold can still have a metallic - like atomic arrangement. Melting is a physical change and doesn't determine if it's a pure substance or a mixture.

Answer:

A. It has a variable composition of other elements and minerals.