Q: Calculate the mass of an electron using the charge-to-mass ratio $$\left( \frac{e}{m} = 1.758820 \times 10^8$ \ \mathrm{C/g} \right)$$ and the charge of an electron $$\left( e = 1.602 \times 10$$^{-19}$$ \ \mathrm{C} \right). $$What is the mass?

$$9.109382 \times 10$$^{-28}$$ \ \mathrm{g}$$

Question 1

Which of the following statements best describes an element?

Accepted Answer

An element is a fundamental substance that cannot be chemically changed or broken down into simpler components.

Question 2

Which property is an example of an intensive property?

Accepted Answer

Density

Question 3

Which group of elements is characterized by being highly reactive, soft, silvery metals that react violently with water?

Accepted Answer

Group 1 - Alkali Metals

Question 4

Which law states that mass is neither created nor destroyed in chemical reactions?

Accepted Answer

Law of Conservation of Mass

Question 5

A sample of water always contains 1 part hydrogen and 8 parts oxygen by mass. This is an example of which law?

Accepted Answer

Law of Definite Proportions

Question 6

Which experiment provided evidence for the existence of electrons as negatively charged subatomic particles?

Accepted Answer

Cathode ray experiment

Question 7

Which of the following is a chemical property?

Accepted Answer

Rusting of iron

Question 8

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 9

Which group on the periodic table contains elements that are colorless, inert gases?

Accepted Answer

Group 18 - Noble Gases

Question 10

Which scientist is credited with the law of multiple proportions?

Accepted Answer

John Dalton

Question 11

A sample contains 12.01 g of carbon and 32.00 g of oxygen. Another sample contains 12.01 g of carbon and 16.00 g of oxygen. According to the law of multiple proportions, what is the ratio of the masses of oxygen that combine with a fixed mass of carbon?

Accepted Answer

$$1:2$$

Question 12

Which of the following best describes a metalloid?

Accepted Answer

An element with properties intermediate between metals and nonmetals.

Question 13

Which of the following is the correct formula for the oxide of gallium, as predicted by Mendeleev?

Accepted Answer

$$\mathrm{Ga}_2\mathrm{O}_3$$

Question 14

Which of the following statements is NOT part of Dalton’s atomic theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 15

Which experiment led to the discovery of the nucleus as a small, dense, positively charged center in the atom?

Accepted Answer

Gold foil experiment

Question 16

Calculate the mass of an electron using the charge-to-mass ratio $$\left( \frac{e}{m} = 1.758820 	imes 10^8$ \ \mathrm{C/g} ight)$$ and the charge of an electron $$\left( e = 1.602 	imes 10$$^{-19}$$ \ \mathrm{C} ight). $$What is the mass?

Accepted Answer

$$9.109382 	imes 10$$^{-28}$$ \ \mathrm{g}$$

Question 17

Which of the following elements is most abundant in the universe?

Accepted Answer

Hydrogen

Question 18

An atom of $$^{75}_{34}\mathrm{Se}$$ has how many protons, neutrons, and electrons?

Accepted Answer

34 protons, 41 neutrons, 34 electrons

Question 19

Which of the following best describes the location and relative mass of subatomic particles in an atom?

Accepted Answer

Protons and neutrons are in the nucleus and have similar mass; electrons are in the electron cloud and have much less mass.

Question 20

Which of the following is a real-world application of the law of conservation of mass?

Accepted Answer

When gasoline combusts in a car engine, the total mass of the products (CO$$_2$$, H$$_2O$$, etc.) equals the total mass of the reactants (gasoline and O$$_2).$$

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