Question 1

Which of the following best describes an intensive property?

Accepted Answer

It does not depend on the amount of substance present.

Question 2

Which of the following is a chemical change?

Accepted Answer

Burning wood in a campfire

Question 3

A student measures the mass of a sample as 0.00450 g. How many significant figures are in this measurement?

Accepted Answer

3

Question 4

Convert 470 nm to meters using the correct metric prefix relationships.

Accepted Answer

$$4.7 	imes 10$$^{-7}$$ m

Question 5

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 6

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

Accepted Answer

$$CH_2O$$

Question 7

Which of the following compounds is ionic?

Accepted Answer

$$NaCl$$

Question 8

What is the correct name for $$N_2O_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 9

A sample contains 3.01 $$	imes$$ $$10^{23}$$ molecules of $$CO_2. $$How many moles of $$CO_2$$ are present?

Accepted Answer

0.50 mol

Question 10

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 11

Calculate the formula weight of $$Ca(OH)_2 ($$atomic weights: Ca = 40.08, O = 16.00, H = 1.01).

Accepted Answer

$$74.10 g/$$mol

Question 12

Which of the following best describes a limiting reagent in a chemical reaction?

Accepted Answer

The reactant that determines the amount of product formed

Question 13

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 14

Which of the following ions is a cation?

Accepted Answer

$$Na^+$$

Question 15

What is the correct formula for a compound formed between $$Al^{3+}$$ and $$SO_4$$^{2-}$$?

Accepted Answer

$$Al_2$$($$SO_4)_3$

Question 16

Which of the following is the correct name for $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 17

A sample of $$Na_2SO_4$$ contains 14.2 g of sodium. What is the mass percent of sodium in $$Na_2SO_4$$? (Na = 22.99, S = 32.07, O = 16.00)

Accepted Answer

$$32.4\%$$

Question 18

Which of the following best describes Avogadro’s number?

Accepted Answer

The number of molecules in 1 mole of a substance

Question 19

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 20

Which of the following is a decomposition reaction?

Accepted Answer

$$2KClO_3 \rightarrow 2KCl + 3O_2$$

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

Study Guide - Practice Questions