Q: Which of the following is the correct formula for calculating percent yield?

$$ \frac{\text{actual yield}}{\text{theoretical yield}} \times 100\% $$

Question 1

Which of the following statements best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in a fixed proportion

Question 2

Which subatomic particle is responsible for the identity of an element?

Accepted Answer

Proton

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 accepted value. This demonstrates:

Accepted Answer

Low accuracy and high precision

Question 4

Which of the following is an example of a chemical change?

Accepted Answer

Rusting of iron

Question 5

What is the correct balanced equation for the decomposition of lead(IV) oxide?

Accepted Answer

$$ 2\mathrm{$$PbO_2$$ \rightarrow 2PbO + O_2$} $$

Question 6

A sample contains 6.02 x $$10^{23}$$ molecules of water. What is the mass of this sample in grams? (Molar mass of water = 18 g/mol)

Accepted Answer

$$ 18  g$$

Question 7

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout

Question 8

Which of the following is the correct electron configuration for potassium ($$Z=19$$)?

Accepted Answer

$$ 1s^2$ 2s^2$ 2p^6$ 3s^2$ 3p^6$ 4s^1$ $$

Question 9

A reaction in which two elements combine to form a single compound is called:

Accepted Answer

Synthesis (combination) reaction

Question 10

Which of the following is NOT a physical property of matter?

Accepted Answer

Ability to rust

Question 11

If 16.0 g of methane ($$\mathrm{CH_4$}) $$reacts with 32.0 g of oxygen ($$\mathrm{O_2$}) to $$produce carbon dioxide and water, what is the limiting reagent?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 12

Which of the following best describes the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction

Question 13

Which of the following is an extensive property of matter?

Accepted Answer

Mass

Question 14

A student mixes two clear solutions and observes the formation of a solid. This solid is called:

Accepted Answer

A precipitate

Question 15

Which of the following is the correct formula for calculating percent yield?

Accepted Answer

$$ \frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\% $$

Question 16

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 17

Which of the following is the correct representation for Avogadro's number?

Accepted Answer

$$ 6.02 	imes 10$$^{23}$$ $$

Question 18

A chemical equation is balanced when:

Accepted Answer

The number of atoms of each element is the same on both sides of the equation

Question 19

Which of the following is a single-replacement reaction?

Accepted Answer

$$ \mathrm{Zn} + 2\mathrm{HCl} \rightarrow \mathrm{$$ZnCl_2$$} + \mathrm{H_2$} $$

Question 20

Which of the following best describes a catalyst in a chemical reaction?

Accepted Answer

A substance that increases the rate of a reaction without being consumed

Introduction to Chemistry: Key Concepts, Definitions, and Applications

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