Question 1

Which of the following statements best explains why water (H$$_2O) $$has very different properties from its constituent elements, hydrogen and oxygen?

Accepted Answer

Water is a compound formed by a chemical combination of hydrogen and oxygen in a fixed ratio, resulting in new properties.

Question 2

Which of the following best describes the difference between a mixture and a compound?

Accepted Answer

A mixture contains elements in any proportion, while a compound contains elements in a fixed, definite ratio.

Question 3

Which of the following is the correct empirical formula for hydrogen peroxide (H$$_2O$_2$$)?

Accepted Answer

$$\mathrm{HO}$$

Question 4

Which of the following compounds is an example of an ionic compound?

Accepted Answer

$$\mathrm{NaCl}$$

Question 5

What is the correct name for the compound Fe$$_2O$_3$$?

Accepted Answer

Iron(III) oxide

Question 6

Which of the following is a polyatomic ion?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 7

What is the correct formula for magnesium nitrate?

Accepted Answer

$$\mathrm{Mg(NO_3$)_2}$$

Question 8

Which of the following is the correct name for the acid H$$_2SO$_4$$?

Accepted Answer

Sulfuric acid

Question 9

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

Accepted Answer

$$\mathrm{CH_2O}$$

Question 10

Which of the following best describes the difference between a molecular formula and an empirical formula?

Accepted Answer

A molecular formula shows the actual number of atoms in a molecule, while an empirical formula shows the simplest whole-number ratio of atoms.

Question 11

What is the formula mass of sodium chloride (NaCl)? (Atomic masses: Na = 22.99 amu, Cl = 35.45 amu)

Accepted Answer

$$22.99 + 35.45 = 58.44$$ amu

Question 12

Which of the following is the correct name for the compound N$$_2O$_4$$?

Accepted Answer

Dinitrogen tetroxide

Question 13

Which of the following is a correct balanced chemical equation for the combustion of methane?

Accepted Answer

$$\mathrm{CH_4$(g) + 2O_2(g) \rightarrow CO_2$(g) + 2H_2O(g)}$$

Question 14

Which of the following is the correct name for the compound CuSO$$_4$$·5H$$_2O$$?

Accepted Answer

Copper(II) sulfate pentahydrate

Question 15

Which of the following is a molecular element?

Accepted Answer

Oxygen (O$$_2)$$

Question 16

What is the correct name for the acid HNO$$_2$$?

Accepted Answer

Nitrous acid

Question 17

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 18

A sample of a compound contains 0.400 mol of C, 0.800 mol of H, and 0.400 mol of O. What is the empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 19

Which of the following best describes a hydrocarbon?

Accepted Answer

A compound containing only carbon and hydrogen

Molecules, Compounds, and Chemical Equations: A Comprehensive Study Guide

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