Q: A student measures the mass of a sample as $$2.50 \times 10$$^{-3}$$ kg. Express this mass in grams using scientific notation.

$$2.50 \times 10$$^{0}$$ \text{ g}$

Q: A sample of a compound contains 12.0 g of carbon and 32.0 g of oxygen. What is the mass percent of carbon in the compound?

$$\frac{12.0}{12.0 + 32.0} \times 100\% = 27.3\%$$

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

$$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$$

Question 1

Which of the following statements best describes the Law of Definite Proportion?

Accepted Answer

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

Question 2

A student measures the mass of a sample as $$2.50 	imes 10$$^{-3}$$ kg. Express this mass in grams using scientific notation.

Accepted Answer

$$2.50 	imes 10$$^{0}$$ 	ext{ g}$

Question 3

Which of the following is NOT a correct SI unit and its corresponding physical quantity?

Accepted Answer

Joule (J) – Mass

Question 4

A sample of a compound contains 12.0 g of carbon and 32.0 g of oxygen. What is the mass percent of carbon in the compound?

Accepted Answer

$$\frac{12.0}{12.0 + 32.0} 	imes 100\% = 27.3\%$$

Question 5

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 6

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

Accepted Answer

J.J. Thomson

Question 7

A student needs to convert 25.0 °C to Kelvin. Which equation should they use, and what is the correct answer?

Accepted Answer

$$K = ^\circ C + 273.15$$; $$K = 25.0 + 273.15 = 298.15 K$$

Question 8

Which of the following is the correct definition of atomic number?

Accepted Answer

The number of protons in the nucleus of an atom.

Question 9

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?

Accepted Answer

$$35 - 17 = 18$$ neutrons

Question 10

Which of the following is a correct statement about isotopes?

Accepted Answer

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

Question 11

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

Accepted Answer

$$	ext{Density} = \frac{	ext{Mass}}{	ext{Volume}}$$

Question 12

A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 13

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electrons between two nonmetal atoms.

Question 14

Which of the following is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 15

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of water. How many moles of water are present?

Accepted Answer

$$0.500$$ mol

Question 16

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

Accepted Answer

Elements in the same group have similar chemical properties.

Question 17

Which of the following is the correct balanced chemical equation for the reaction of hydrogen gas with oxygen gas to form water?

Accepted Answer

$$2\mathrm{H_2$}(g) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{H_2O}(l)$$

Question 18

A student is asked to calculate the energy of a moving object with a mass of 2.0 kg and a velocity of 3.0 m/s. Which formula should they use, and what is the kinetic energy?

Accepted Answer

$$KE = \frac{1}{2}mv^2$; KE$$ = \frac{1}{2} 	imes 2.0 	imes $$(3.0)^2 = 9.0$ J

Question 19

Which of the following is the correct name for $$\mathrm{Na_2SO_4}$$?

Accepted Answer

Sodium sulfate

Question 20

Which of the following is a correct statement about Avogadro's number?

Accepted Answer

It is the number of particles in one mole of a substance, $$6.022 	imes 10$$^{23}$$.

General Chemistry I: Exam 1 Study Guide and Key Concepts

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