Question 1

Which of the following best describes a compound?

Accepted Answer

A substance formed when two or more different elements chemically combine in fixed proportions.

Question 2

Which equation correctly represents the reaction between magnesium and hydrochloric acid?

Accepted Answer

$$\mathrm{Mg} + 2\mathrm{HCl} \rightarrow \mathrm{MgCl}_2 + \mathrm{H}_2$$

Question 3

A student bubbles carbon dioxide through limewater. What observation and chemical equation best describe this test?

Accepted Answer

The limewater turns milky; $$\mathrm{Ca(OH)}_2(aq) + \mathrm{CO}_2(g) \rightarrow \mathrm{CaCO}_3(s) + \mathrm{H}_2O(l)$$

Question 4

Which of the following is the correct ionic equation for the reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

$$\mathrm{H}^+(aq) + \mathrm{OH}^-(aq) \rightarrow \mathrm{H}_2O(l)$$

Question 5

A sample contains $$1.25\ \mathrm{g} of $$water. How many molecules of water are present? ($$M_r of$$ $$\mathrm{H}_2O = 18)$$

Accepted Answer

$$4.18 	imes 10$$^{22}$$

Question 6

Which of the following best describes a displacement reaction?

Accepted Answer

A reaction in which one element replaces another, less reactive element in a compound.

Question 7

Calculate the empirical formula for a compound containing 34.3% Na, 17.9% C, and 47.8% O by mass. (Ar: Na = 23, C = 12, O = 16)

Accepted Answer

$$\mathrm{Na}_2\mathrm{CO}_2$$

Question 8

Which of the following is the correct balanced equation for the reaction of zinc with hydrochloric acid?

Accepted Answer

$$\mathrm{Zn} + 2\mathrm{HCl} \rightarrow \mathrm{ZnCl}_2 + \mathrm{H}_2$$

Question 9

Which of the following is the correct formula for calculating the number of moles from mass and molar mass?

Accepted Answer

$$n = \frac{m}{M}$$

Question 10

A gas occupies $$4.8\ \mathrm{dm}^3 at $$room temperature and pressure. How many moles of gas are present? (Molar volume at r.t.p. = $$24\ \mathrm{dm}^3)$$

Accepted Answer

$$0.20$$ moles

Question 11

Which of the following statements about atom economy is correct?

Accepted Answer

Addition reactions have 100% atom economy.

Question 12

Which of the following is the correct ionic equation for the test for sulfate ions?

Accepted Answer

$$\mathrm{Ba}^{2+}(aq) + \mathrm{SO}_4$$^{2-}$$(aq) \rightarrow \mathrm{BaSO}_4(s)$$

Question 13

A reaction produces 8.0 g of product, but the theoretical yield is 10.0 g. What is the percentage yield?

Accepted Answer

$$80\%$$

Question 14

Which of the following is the correct ideal gas equation?

Accepted Answer

$$pV = nRT$$

Question 15

Which of the following is the correct sequence for determining the empirical formula from experimental data?

Accepted Answer

Convert mass to moles, divide by smallest number, write ratio.

Question 16

Which of the following is a correct description of a molecule?

Accepted Answer

A group of two or more atoms chemically bonded together.

Question 17

A solution contains $$0.5\ \mathrm{mol} of $$solute in $$1.0\ \mathrm{dm}^3 of $$solution. What is its molar concentration?

Accepted Answer

$$0.5\ \mathrm{mol\ dm}^{-3}$$

Question 18

Which of the following is the correct ionic equation for the test for chloride ions?

Accepted Answer

$$\mathrm{Ag}^+(aq) + \mathrm{Cl}^-(aq) \rightarrow \mathrm{AgCl}(s)$$

Question 19

Which of the following is the correct definition of relative atomic mass ($$A_r$$)?

Accepted Answer

The weighted mean mass of an atom compared to $$\frac{1}{12} of $$the mass of a $$^{12}\mathrm{C}$$ atom.

Formulae, Equations, and Amount of Substances: Introductory Chemistry Study Guide

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