Question

What do these two changes have in common?

your breath becoming visible on a cold day
ice crystals forming on a window
Select all that apply.
Both are only physical changes,
Both conserve mass,
Both are changes of state,
Both are chemical changes,

Answer 1

Both the visibility of your breath on a cold day and the formation of ice crystals on a window are examples of physical changes, involving a change of state and conserving mass. They are not chemical changes.

Step-by-step explanation:

Both the visibility of your breath on a cold day and the formation of ice crystals on a window are examples of physical changes. Physical changes alter the appearance of a substance without changing its molecular structure. In both cases, the composition of the molecules remains the same even though their physical properties change. For example, when water vapor in your breath comes into contact with the cold air, it condenses into tiny droplets or ice crystals, but the molecules of water remain the same.

Both changes also involve a change of state. The visibility of your breath becoming visible on a cold day is due to the change of state from water vapor (gas) to liquid droplets. The ice crystals forming on a window occur when the water vapor in the air comes into contact with the cold window surface and freezes, changing from gas to solid.

Thus, both changes are physical changes and involve a change of state, while conserving mass and not being chemical changes.