Question 1

Which statement best describes the Law of Conservation of Mass as it applies to a chemical reaction?

Accepted Answer

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

Question 2

A student measures the volume of liquid in a graduated cylinder and reads the value at the top of the meniscus. What is the most accurate way to read the volume?

Accepted Answer

Estimate the last digit and read from the bottom of the meniscus.

Question 3

Which experiment led to the discovery of the electron and its charge?

Accepted Answer

Cathode ray tube experiment

Question 4

Given the isotope symbol $$\mathrm{^{35}_{17}Cl}$$, how many neutrons does this atom have?

Accepted Answer

18

Question 5

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

Accepted Answer

Atoms are composed of protons, neutrons, and electrons.

Question 6

A sample of water contains 16 g of oxygen and 2 g of hydrogen. What is the mass ratio of oxygen to hydrogen in water?

Accepted Answer

$$8:1$$

Question 7

Which group on the periodic table contains elements that are mostly unreactive?

Accepted Answer

Noble gases

Question 8

If you have 35.2 g of $$\mathrm{CO_2$}$$, how many grams of oxygen are present? (Given mass ratio $$\mathrm{O:C} = 8:3)$$

Accepted Answer

$$25.6\ \mathrm{g}$$

Question 9

Which property is NOT characteristic of metals?

Accepted Answer

Poor conductor of electricity

Question 10

Which law states that all samples of a given compound have the same proportions of their constituent elements?

Accepted Answer

Law of Definite Proportions

Question 11

A chromium atom has 24 protons, 28 neutrons, and 24 electrons. What is its isotope symbol?

Accepted Answer

$$\mathrm{^{52}_{24}Cr}$$

Question 12

Which element is a metalloid?

Accepted Answer

Arsenic

Question 13

Which of the following best describes the Law of Multiple Proportions?

Accepted Answer

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.

Question 14

Which subatomic particle determines the identity of an element?

Accepted Answer

Proton

Question 15

Which of the following is true about nonmetals?

Accepted Answer

They are generally poor conductors of heat and electricity.

Question 16

What is the atomic mass of an element with two isotopes: 60.15% with mass 58 amu and 39.85% with mass 60 amu?

Accepted Answer

$$58.8\ \mathrm{amu}$$

Question 17

Which group on the periodic table contains the most reactive nonmetals?

Accepted Answer

Halogens

Question 18

Which of the following ions has a charge of $$+2$$?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$}$$

Question 19

Which statement about isotopes is correct?

Accepted Answer

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

Question 20

Which of the following best explains why the atomic mass of an element is not a whole number?

Accepted Answer

It is the weighted average of the masses of all naturally occurring isotopes.

Atoms, Elements, and the Foundations of Atomic Theory

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