You mix them without measuring anything out.
A chemical reaction causes substances to combine in different ways to make other substances.
An equal amount "matches" each other. So, if you are told to combine milk and water in equal amounts, with the total amount specified as "one cup", the milk would be 1/2 cup and the water 1/2 cup. There are many situations in life where you'll need to know what to do to combine substances in "equal amounts".
When substances combine and retain their own properties, the result is a mixture.
Reactants are substances that can combine in a chemical reaction.
These substances are called reactants.
i have no idea :)
These substances form a mixture.
Release large amounts of SO2 and NOx into the air. Those substances combine with water vapor in the atmosphere to form acid rain.
helium does not combine with any element
This is called diffusion. Substances move randomly, from an area of high concentration to an area of low concentration. Osmosis is a specific type of diffusion that only involves the random movement of water.
when substances are combined it is sometimes called a mixture.
These substances form a mixture.