Answer
1.a) Dry ice consists of only solid CO2 (Carbon dioxide) and is therefore considered a pure substance.
Work Step by Step
9 K Gold is a mixture of various metals, which can include bronze, brass, steel, and so on. Dry air is a mixture of elements such as Nitrogen and Oxygen. Blood consists of plasma, which is made up of a mixture of salts, water, and proteins. None of these can, therefore, be considered pure.
