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

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

Question 1

Which of the following statements best describes the difference between a hypothesis and a scientific theory?

Accepted Answer

A hypothesis is a tentative explanation that can be tested, while a scientific theory is a well-substantiated explanation based on a body of evidence.

Question 2

Which of the following is an example of a heterogeneous mixture?

Accepted Answer

A salad with lettuce, tomatoes, and cucumbers

Question 3

A student measures the mass of a sample three times and gets values that are very close to each other, but far from the true value. This indicates the measurements are:

Accepted Answer

Precise but not accurate

Question 4

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to air

Question 5

Which law states that in a chemical reaction, matter is neither created nor destroyed?

Accepted Answer

Law of Conservation of Mass

Question 6

Convert $$25.0 \, ^\circ\mathrm{C} to $$Kelvin.

Accepted Answer

$$298.2 \, \mathrm{K}$$

Question 7

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 8

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

Accepted Answer

17 protons, 18 neutrons, 17 electrons

Question 9

Which of the following elements is an alkali metal?

Accepted Answer

Sodium ($$\mathrm{Na})$$

Question 10

Which of the following compounds is held together by ionic bonds?

Accepted Answer

Sodium chloride ($$\mathrm{NaCl})$$

Question 11

What is the empirical formula of a compound that contains 40.0\% carbon, 6.7\% hydrogen, and 53.3\% oxygen by mass?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 12

How many moles are in $$3.01 	imes 10$$^{23}$$ molecules of water?

Accepted Answer

$$0.500$$ moles

Question 13

Which of the following is the correct name for $$\mathrm{Fe_2O_3}$$?

Accepted Answer

Iron(III) oxide

Question 14

A sample contains $$0.250$$ moles of $$\mathrm{NaCl}. $$What is the mass of the sample? ($$\mathrm{Na} = 23.0 \, \mathrm{g/mol}$$, $$\mathrm{Cl} = 35.5 \, \mathrm{g/mol})$$

Accepted Answer

$$14.6 g$$

Question 15

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

Accepted Answer

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

Question 16

Which of the following is a physical property?

Accepted Answer

Melting point

Question 17

Which of the following is the correct formula for dinitrogen pentoxide?

Accepted Answer

$$\mathrm{N_2O_5}$$

Question 18

A compound is found to contain $$24.0 g of $$carbon, $$4.0 g of $$hydrogen, and $$32.0 g of $$oxygen. What is the empirical formula?

Accepted Answer

$$\mathrm{C_2H_4O_2}$$

Question 19

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 20

Which of the following is the correct name for $$\mathrm{K_2SO_4}$$?

Accepted Answer

Potassium sulfate

General Chemistry I: Study Guide – Matter, Measurement, Atoms, and Compounds

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