Statement one mass is conserved during this reaction. Statement to type of atoms are conserved during the reaction. Which statement is true for both chemical reaction in a nuclear reaction

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Trumpeter a holds a b-flat note on the trumpet for a long time. person c is running towards the trumpeter at a constant velocity. person b is running away from the trumpeter at the same rate. person d is standing still the whole time. which person hears a frequency that is lower than the b-flat?

Asample of a gaseous substance changes into a liquid