Which of these mixtures are heterogeneous?

A.) granite

B.) brass

C.) salt and water

D.) oil and water

The correct answers are A. Granite and D. Oil and water

That is because heterogeneous means that you can see the constituents of a compound, that is, here you can easily see both water and oil or the parts of a granite. Other mentioned compounds are homogeneous which means that their constituents cannot be seen separately.

Heterogenous mixtures are mixtures that when samples are obtained from diffent parts of the mixtures, the parts are not necessarily the same. This is different to the other type of mixture which is the homogenous mixture which are completely uniform throughout the mixture. Answer is D since oil and water are immiscible