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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