Q: A compound contains 40.0 g of carbon and 60.0 g of oxygen. What is the percent composition by mass of carbon in the compound?

$\dfrac{40.0}{40.0 + 60.0} \times 100 = 40.0\%$

Q: Which of the following is the correct definition of Avogadro's number?

The number of particles in one mole, $6.022 \times 10^{23}$.

Q: Which of the following is the correct formula for calculating percent composition by mass of an element in a compound?

$\dfrac{\text{mass of element in 1 mole of compound}}{\text{molar mass of compound}} \times 100$

Question 1

Which of the following statements best describes the difference between a law and a theory in scientific knowledge?

Accepted Answer

A law is a summary of observed phenomena, while a theory provides an explanation for those phenomena.

Question 2

Which of the following is the correct SI unit for measuring energy?

Accepted Answer

$\mathrm{J}$ (Joule)

Question 3

A student measures the mass of a sample as 0.00560 kg. Express this value in scientific notation.

Accepted Answer

$5.60 	imes 10^{-3}$ kg

Question 4

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 5

Which scientist is credited with discovering the electron using the cathode ray tube experiment?

Accepted Answer

J.J. Thomson

Question 6

A compound contains 40.0 g of carbon and 60.0 g of oxygen. What is the percent composition by mass of carbon in the compound?

Accepted Answer

$\dfrac{40.0}{40.0 + 60.0} 	imes 100 = 40.0\%$

Question 7

Which of the following is NOT a fundamental SI unit?

Accepted Answer

Liter ($\mathrm{L}$)

Question 8

Which statement about isotopes is correct?

Accepted Answer

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

Question 9

Which of the following is the correct formula for calculating density?

Accepted Answer

$\mathrm{Density} = \dfrac{\mathrm{Mass}}{\mathrm{Volume}}$

Question 10

A sample of water has a mass of 250 g and a volume of 250 mL. What is its density in $\mathrm{g/mL}$?

Accepted Answer

$1.0\ \mathrm{g/mL}$

Question 11

Which of the following is the correct conversion equation from Celsius to Kelvin?

Accepted Answer

$K = ^\circ C + 273.15$

Question 12

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the components are not evenly distributed and can be distinguished.

Question 13

Which of the following is the correct definition of Avogadro's number?

Accepted Answer

The number of particles in one mole, $6.022 	imes 10^{23}$.

Question 14

Which of the following compounds is an example of a molecular compound?

Accepted Answer

$\mathrm{CO_2}$

Question 15

Which of the following is the correct formula for calculating kinetic energy?

Accepted Answer

$KE = \dfrac{1}{2}mv^2$

Question 16

Which of the following statements about the atomic number is correct?

Accepted Answer

The atomic number is the number of protons in an atom.

Question 17

Which of the following is the correct formula for water?

Accepted Answer

$\mathrm{H_2O}$

Question 18

Which of the following is a correct statement about the Law of Conservation of Mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 19

Which of the following is the correct formula for calculating percent composition by mass of an element in a compound?

Accepted Answer

$\dfrac{	ext{mass of element in 1 mole of compound}}{	ext{molar mass of compound}} 	imes 100$

General Chemistry I: Key Concepts and Study Guide

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