Question 1

Which of the following statements best describes the law of constant composition?

Accepted Answer

A compound always contains the same elements in the same proportion by mass.

Question 2

Which scientist is credited with discovering the law of conservation of mass?

Accepted Answer

Antoine Lavoisier

Question 3

According to Dalton’s atomic theory, which postulate explains why the mass of reactants equals the mass of products in a chemical reaction?

Accepted Answer

Atoms are neither created nor destroyed in chemical reactions.

Question 4

Which law states that when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers?

Accepted Answer

Law of multiple proportions

Question 5

If 10.0 g of hydrogen reacts with 80.0 g of oxygen to form water, what is the total mass of water produced according to the law of conservation of mass?

Accepted Answer

$90.0\ \mathrm{g}$

Question 6

Which of the following is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 7

Carbon monoxide ($\mathrm{CO}$) and carbon dioxide ($\mathrm{CO_2}$) are examples used to illustrate which chemical law?

Accepted Answer

Law of multiple proportions

Question 8

Which of the following compounds has a different empirical formula than its molecular formula?

Accepted Answer

$\mathrm{C_2H_4}$

Question 9

A sample of water from two different sources is analyzed and found to contain 11.1% hydrogen and 88.9% oxygen by mass. This observation supports which law?

Accepted Answer

Law of constant composition

Question 10

Which of the following best explains why Dalton’s atomic theory was a significant advancement in chemistry?

Accepted Answer

It organized existing chemical laws into a unified theory of matter.

Question 11

If two compounds are formed from the same two elements, and the ratio of the masses of one element that combine with a fixed mass of the other is 2:1, which law does this illustrate?

Accepted Answer

Law of multiple proportions

Question 12

Which of the following is a direct consequence of Dalton’s postulate that atoms are neither created nor destroyed in chemical reactions?

Accepted Answer

The mass of the products equals the mass of the reactants.

Question 13

Which statement is true according to Dalton’s atomic theory?

Accepted Answer

Atoms of different elements have different properties.

Question 14

Which of the following is an example of the law of constant composition?

Accepted Answer

Water from any source always contains two hydrogen atoms for each oxygen atom.

Question 15

Which of the following is NOT supported by Dalton’s atomic theory?

Accepted Answer

Atoms can be converted into other elements by chemical reactions.

Question 16

Which of the following pairs of compounds best illustrates the law of multiple proportions?

Accepted Answer

$\mathrm{CO}$\ and\ $\mathrm{CO_2}$

Question 17

Which postulate of Dalton’s atomic theory is directly related to the law of constant composition?

Accepted Answer

Compounds are formed when atoms of more than one element combine in fixed ratios.

Question 18

Which of the following would violate Dalton’s atomic theory?

Accepted Answer

Atoms of hydrogen are converted into atoms of helium in a chemical reaction.

Question 19

Which of the following is a limitation of Dalton’s atomic theory based on modern scientific understanding?

Accepted Answer

Atoms of the same element can have different masses due to isotopes.

Atoms, Molecules, and Atomic Theory: Foundations of Chemistry

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