Chemistry Unit 3 Practice Test

A certain compound is composed of elements A and B. It always has the same mass ratio of A to B because

• all atoms have the same mass.

• A and B have characteristic masses.

• A and B have identical masses.

• any excess A or B will be destroyed

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NGSS.HS-PS1-7

Carbon dioxide or CO₂ will always be a 1 to 2 ratio of carbon to oxygen according to the Law of Definite Proportions.

• True

• False

If 2 g of element K combine with 10 g of element L, how many grams of element K combine with 20 g of element L?

• 10 g

• 4 g

• 20 g g

• 5 g

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NGSS.HS-PS1-7

The two oxides of carbon, CO and CO_2, are explained by the

• periodic law.

• law of multiple proportions.

• atomic law

• law of conservation of mass

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NGSS.HS-PS1-7

If two or more compounds are composed of the same two elements, the ratio of the masses of one element that combine with a fixed mass of the other element is a simple whole number. This is a statement of the law of

• conservation of mass.

• mass action.

• multiple proportions

• definite proportions

If 3 g of element C combine with 8 g of element D to form compound CD, how many grams of D are needed to form compound CD₃?

• 8 g

• 16 g

• 24 g

• 19 g

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NGSS.HS-PS1-7

Oxygen can combine with nitrogen to form two compounds, nitrogen monoxide and nitrogen dioxide. The ratio of the masses of oxygen that combine with a given mass of nitrogen is 1:2. This is an example of

• the law of conservation of mass.

• the law of conservation of energy.

• the law of multiple proportions.

• Dalton's atomic theory

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NGSS.HS-PS1-7

According to the law of definite proportions, any two samples of H₂O have

• the same mass.

• slightly different molecular structures.

• the same melting point

• the same ratio of elements

Who was the Russian scientist who studied chemistry and organized the periodic table by atomic mass?

• John Dalton

• Robert Brown

• Jons Berzelius

• Dmitri Mendeleev

Who was the English scientist who first recognized that the ratio of the number of atoms that combine is the same as the ratio of the masses that combine?

• John Dalton

• Jon Newlands

• Edward Morley

• Jons Berzelius

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NGSS.HS-PS1-7