Q: Which of the following best describes Avogadro’s number?

The number of particles in one mole of a substance: $6.022 \times 10^{23}$

Question 1

Which of the following best describes the difference between a chemical change and a physical change?

Accepted Answer

A chemical change alters the composition of a substance, while a physical change does not.

Question 2

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 3

A sample contains 25.0 grams of NaCl. What is this mass in milligrams (mg)?

Accepted Answer

$2.50 	imes 10^4$ mg

Question 4

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 5

What is the empirical formula for a compound with the molecular formula $C_6H_{12}O_6$?

Accepted Answer

$CH_2O$

Question 6

Which of the following compounds is an ionic compound?

Accepted Answer

NaBr

Question 7

How many moles are in $3.01 	imes 10^{23}$ molecules of $CO_2$?

Accepted Answer

0.500 mol

Question 8

Which of the following is the correct name for $N_2O_5$?

Accepted Answer

Dinitrogen pentoxide

Question 9

A reaction has a theoretical yield of 10.0 g, but only 7.5 g of product is actually obtained. What is the percent yield?

Accepted Answer

$75\%$

Question 10

Which of the following best describes Avogadro’s number?

Accepted Answer

The number of particles in one mole of a substance: $6.022 	imes 10^{23}$

Question 11

Which of the following is the correct formula for aluminum sulfate?

Accepted Answer

$Al_2(SO_4)_3$

Question 12

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

$CH_2O$

Question 13

Which of the following is a correct statement about the arrangement of subatomic particles in an atom?

Accepted Answer

Protons and neutrons are located in the nucleus, while electrons are found outside the nucleus.

Question 14

Which of the following is the correct balanced equation for the combustion of methane ($CH_4$) in oxygen?

Accepted Answer

$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$

Question 15

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 16

What is the formula weight (FW) of $H_2SO_4$? (Atomic weights: H = 1.01, S = 32.07, O = 16.00)

Accepted Answer

$98.09$ amu

Question 17

Which of the following is the correct name for $PCl_5$?

Accepted Answer

Phosphorus pentachloride

Question 18

A student mixes 10.0 g of $AgNO_3$ with 10.0 g of $NaCl$ in water. The reaction is: $AgNO_3 + NaCl \rightarrow AgCl + NaNO_3$. Which reactant is the limiting reagent? (Molar masses: $AgNO_3 = 169.87$ g/mol, $NaCl = 58.44$ g/mol)

Accepted Answer

$AgNO_3$

Question 19

Which of the following is the correct formula for the compound formed between calcium ions and nitrate ions?

Accepted Answer

$Ca(NO_3)_2$

Chem121A Exam 1 Study Guide: Matter, Atoms, and Chemical Reactions

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