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Why was 1990 an important year regarding air quality? Check all that apply.
2.Cost-effective ways to reduce pollution were emphasized.
4.Modifications and improvements were made to the Clean Air Act.
i just took the test this is 100% correct
By adding together the number of protons and neutrons and multiplying by 1 amu, you can calculate the mass of the atom.
Answer:
In a chemical reaction, there is a change in the composition of the substances; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition.
Explanation: