Which of the following is a homogeneous mixture?

• A. Sand and water
• B. Rice and beans
• C. Mud in water
• D. Salt water

Answer: (D)

A homogeneous mixture has a uniform composition throughout the sample, so you can’t tell the different components apart by eye. When table salt dissolves in water, the salt ions disperse evenly among the water molecules to form one kind of substance—salt water. You can’t see separate salt particles, and the solution has the same composition wherever you sample it.

The other options don’t form a single phase. Sand and water keep distinct parts—solid sand grains and liquid water—so the mixture isn’t uniform. Rice and beans are two separate foods mixed together but not dissolved, so you can still identify the components. Mud in water contains solid particles that either float or settle, so it’s not a single uniform phase either.