Question 1

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

Accepted Answer

A compound always contains the same elements in the same proportion by mass, regardless of the sample source.

Question 2

Which experiment led to the discovery of the electron and allowed for the calculation of its charge-to-mass ratio?

Accepted Answer

Thomson's cathode ray tube experiment

Question 3

According to Dalton’s atomic theory, which statement is INCORRECT based on modern knowledge?

Accepted Answer

Atoms of a given element are identical in mass and properties.

Question 4

Which law is illustrated by the fact that 12 g of carbon always combines with 32 g of oxygen to form 44 g of carbon dioxide?

Accepted Answer

Law of conservation of mass

Question 5

A sample of a compound contains 40 g of carbon and 53.3 g of oxygen. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CO}_2$$

Question 6

Which of the following statements about isotopes is TRUE?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 7

Which of the following is a correct representation of an atom with 17 protons, 18 neutrons, and 17 electrons?

Accepted Answer

$$^{35}_{17}\mathrm{Cl}$$

Question 8

Which of the following ions is a polyatomic cation?

Accepted Answer

$$\mathrm{NH}_4^+$$

Question 9

What is the correct name for $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 10

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms of each element in a molecule, while an empirical formula shows the lowest whole-number ratio.

Question 11

Which of the following elements is a diatomic molecule in its natural state?

Accepted Answer

Oxygen

Question 12

What is the correct formula for the compound formed between aluminum and sulfate?

Accepted Answer

$$\mathrm{Al}_2(\mathrm{SO}_4)_3$$

Question 13

Which of the following is the correct name for $$\mathrm{HNO}_2$$?

Accepted Answer

Nitrous acid

Question 14

A sample of a compound contains 24 g of carbon and 8 g of hydrogen. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_4$$

Question 15

Which of the following is a metalloid?

Accepted Answer

Silicon

Question 16

Which of the following is the correct name for $$\mathrm{N}_2\mathrm{O}_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 17

Which of the following statements about the periodic table is TRUE?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 18

What is the charge on the ion formed when a magnesium atom loses two electrons?

Accepted Answer

$$2+$$

Question 19

Which of the following is the correct formula for ammonium phosphate?

Accepted Answer

$$\mathrm{(NH}_4)_3\mathrm{PO}_4$$

Question 20

Which of the following is the correct name for $$\mathrm{CCl}_4$$?

Accepted Answer

Carbon tetrachloride

Atoms, Molecules, and Atomic Theory: Foundational Concepts in Chemistry

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