Which of these is NOT an example of a pure substance? A a tablet of the element known as calcium B a glass of muddy water
C a glass of ice and water
D a chemical compound known as aluminium oxide

a glass of muddy water

Explanation:

Pure substances contain only one element or compound.

Calcium is one element so it is a pure substance. Ice and water have the same molecular structure, so it is a pure substance. Aluminum oxide is a chemically pure compound.

The only example that is not a pure substance is muddy water due to the multiple components of mud mixing with the components of water.

Hope that helps.

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.

i believe it would be c: tons.