An unknown amount of a compound with a molecular mass of is dissolved in a 10 ml volumetric flask. a 1.00 ml aliquot of this solution is transferred to a 25 ml volumetric flask, and enough water is added to dilute to the mark. the absorbance of this diluted solution at is in a 1.000 cm cuvette. the molar absorptivity for this compound at is what is the concentration of the compound in the cuvette? concentration: what is the concentration of the compound in the 10 ml flask? concentration: how many milligrams of compound were used to make the 10 ml solution? mass:

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

the population of unionid mussels in the hudson river decreased after zebra mussels were introduced. zebra mussels, a nonnative species, competed with the unionid mussels for food. the zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. the unionid mussel population decreased due to a lack of food.

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