Key Concepts in Chemistry: Master the Fundamentals of Chemistry

Question 1

What is the chemical symbol for potassium?

Accepted Answer

K

Answer

Po

Answer

P

Answer

Pt

Question 2

Which of the following reactions is an example of a combustion reaction?

Accepted Answer

CH₄ + 2O₂ → CO₂ + 2H₂O

Answer

2Na + Cl₂ → 2NaCl

Answer

NaOH + HCl → NaCl + H₂O

Answer

CuO + H₂ → Cu + H₂O

Question 3

Which of the following is not a renewable energy source?

Accepted Answer

Natural gas

Answer

Solar energy

Answer

Wind energy

Answer

Hydroelectric power

Question 4

What is the molecular formula of propane?

Accepted Answer

C₃H₈

Answer

CH₄

Answer

C₂H₄

Answer

C₃H₆

Question 5

Which of the following is the weakest acid?

Accepted Answer

Acetic acid

Answer

Hydrochloric acid

Answer

Nitric acid

Answer

Sulfuric acid

Question 6

What is the hybridization of the nitrogen atom in ammonia (NH₃)?

Accepted Answer

sp³

Answer

sp

Answer

sp²

Answer

sp³d

Question 7

Which of the following particles is NOT a fundamental building block of atoms?

Accepted Answer

Photon

Answer

Proton

Answer

Neutron

Answer

Electron

Question 8

Which type of chemical bond results from the attraction between oppositely charged ions?

Accepted Answer

Ionic

Answer

Covalent

Answer

Metallic

Answer

Hydrogen

Question 9

Determine the formula of the ionic compound formed between sodium and chlorine:

Accepted Answer

NaCl

Answer

Na2Cl

Answer

Na2Cl2

Answer

NaCl2

Question 10

Calculate the mole fraction of a solution that contains 1 mole of solute dissolved in 4 moles of solvent:

Accepted Answer

0.25

Answer

0.2

Answer

0.5

Answer

0.75

Question 11

Which of the following acids is considered a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Ammonium hydroxide

Question 12

Identify the term for the process where a gas dissolves into a liquid:

Accepted Answer

Dissolution

Answer

Evaporation

Answer

Condensation

Answer

Diffusion

Question 13

Which of the following is not a fundamental subatomic particle?

Accepted Answer

Meson

Answer

Proton

Answer

Neutron

Answer

Electron

Question 14

What type of bond is formed through electrostatic attraction between oppositely charged ions?

Accepted Answer

Ionic bond

Answer

Covalent bond

Answer

Metallic bond

Answer

Hydrogen bond

Question 15

What type of reaction absorbs energy from its surroundings?

Accepted Answer

Endothermic reaction

Answer

Exothermic reaction

Answer

Redox reaction

Answer

Precipitation reaction

Question 16

What is the equilibrium constant for a reversible reaction?

Accepted Answer

The ratio of product to reactant concentrations at equilibrium

Answer

The ratio of reactant to product concentrations at equilibrium

Answer

The sum of the reactant and product concentrations at equilibrium

Answer

The difference between the reactant and product concentrations at equilibrium

Question 17

Which of the following is an aromatic functional group?

Accepted Answer

Benzene ring

Answer

Alkyl

Answer

Alkenyl

Answer

Alkynyl

Question 18

Electronegativity measures an atom's ability to draw electrons. How does electronegativity generally change as you move from left to right across a period in the periodic table?

Accepted Answer

Increases

Answer

Decreases

Answer

Stays the same

Answer

Increases from top to bottom

Question 19

Which of the following is the electronic configuration of a neon atom?

Accepted Answer

2, 8

Answer

2, 6

Answer

2, 7

Answer

2, 9

Question 20

What is the group name of the elements in the periodic table that are highly reactive and easily form ions?

Accepted Answer

Alkali metals

Answer

Halogens

Answer

Noble gases

Answer

Transition metals

Question 21

Which type of chemical bond involves the sharing of electrons between atoms?

Accepted Answer

Covalent bond

Answer

Ionic bond

Answer

Metallic bond

Answer

Hydrogen bond

Question 22

Which of the following chemical equations is balanced?

Accepted Answer

2C2H6 + 7O2 → 4CO2 + 6H2O

Answer

CH4 + O2 → CO + H2O

Answer

Fe + HCl → FeCl2 + H2

Answer

NaOH + H2SO4 → Na2SO4 + HOH

Question 23

What is the purpose of using a catalyst in a chemical reaction?

Accepted Answer

To decrease the activation energy of the reaction.

Answer

To increase the activation energy of the reaction.

Answer

To change the products of the reaction.

Answer

To prevent the reaction from occurring.

Question 24

Which element is classified as a metalloid?

Accepted Answer

Silicon

Answer

Sodium

Answer

Chlorine

Answer

Calcium

Question 25

Which type of chemical bond involves the sharing of electrons?

Accepted Answer

Covalent bond

Answer

Ionic bond

Answer

Hydrogen bond

Answer

Metallic bond

Question 26

Which equation represents a balanced chemical equation for the reaction between sodium and chlorine?

Accepted Answer

2Na + Cl2 → 2NaCl

Answer

Na + Cl2 → NaCl

Answer

Na + 2Cl → NaCl2

Answer

2Na + Cl → 2NaCl

Question 27

A catalyst is a substance that:

Accepted Answer

Increases the rate of a reaction without being consumed

Answer

Is consumed in a reaction

Answer

Decreases the rate of a reaction

Answer

Forms the final product

Question 28

What is the equilibrium constant expression for the reaction: A + B ⇌ C?

Accepted Answer

Kc = [C]/[A][B]

Answer

Kc = [A][B]/[C]

Answer

Kc = [C]2/[A][B]

Answer

Kc = [A][B]2/[C]

Question 29

Determine the electron configuration of nitrogen. Which of the following options is correct?

Accepted Answer

1s2 2s2 2p3

Answer

1s2 2s3 2p2

Answer

1s2 2s4 2p1

Answer

1s2 2s2 2p4

Question 30

When atoms share electrons, what type of chemical bond is formed?

Accepted Answer

Covalent

Answer

Ionic

Answer

Metallic

Answer

Hydrogen

Question 31

Identify the name of the compound represented by the formula NaCl.

Accepted Answer

Sodium chloride

Answer

Sodium nitrate

Answer

Sodium carbonate

Answer

Sodium sulfate

Question 32

Calculate the molar mass of carbon dioxide (CO2).

Accepted Answer

44 g/mol

Answer

28 g/mol

Answer

32 g/mol

Answer

56 g/mol

Question 33

Identify the redox reaction among the following options.

Accepted Answer

Combustion of propane

Answer

Dissolution of sugar in water

Answer

Reaction of an acid with a base

Answer

Precipitation of a salt

Question 34

Which chemical symbol represents the element sodium?

Accepted Answer

Na

Answer

Nat

Answer

So

Answer

Sd

Question 35

Which non-metal is the most reactive?

Accepted Answer

Fluorine

Answer

Chlorine

Answer

Oxygen

Answer

Nitrogen

Question 36

Which type of chemical bond results from the sharing of electrons?

Accepted Answer

Covalent bond

Answer

Metallic bond

Answer

Ionic bond

Answer

Hydrogen bond

Question 37

What is the oxidation number of carbon in carbon dioxide (CO2)?

Accepted Answer

+4

Answer

-4

Answer

+2

Answer

0

Question 38

Which of the following is a greenhouse gas?

Accepted Answer

Carbon dioxide

Answer

Nitrogen

Answer

Oxygen

Answer

Helium

Question 39

Which of the following is a redox reaction?

Accepted Answer

Zn + 2HCl → ZnCl2 + H2

Answer

NaCl + AgNO3 → AgCl + NaNO3

Answer

2H2 + O2 → 2H2O

Answer

CaCO3 → CaO + CO2

Question 40

The atomic number of an element is equivalent to the number of:

Accepted Answer

Protons

Answer

Neutrons

Answer

Nucleons

Answer

Electrons

Question 41

In the periodic table, which group comprises the most reactive metals?

Accepted Answer

Group 1

Answer

Group 17

Answer

Group 18

Answer

Transition Metals

Question 42

The process by which atoms gain or lose electrons is called:

Accepted Answer

Ionization

Answer

Reduction

Answer

Combustion

Answer

Oxidation

Question 43

Which of the following reactions represents a neutralization reaction?

Accepted Answer

Acid + Base → Salt + Water

Answer

Ester + Water → Alcohol + Acid

Answer

Combustible + Oxygen → Carbon Dioxide + Water

Answer

Metal + Acid → Salt + Hydrogen

Question 44

Which factor can increase the rate of a chemical reaction?

Accepted Answer

Increasing temperature

Answer

Decreasing concentration

Answer

Adding an inert gas

Question 45

Identify the strongest acid from the following:

Accepted Answer

Hydrochloric acid (HCl)

Answer

Acetic acid (CH3COOH)

Answer

Carbonic acid (H2CO3)

Answer

Ammonia (NH3)

Question 46

The pH of a solution signifies its:

Accepted Answer

Acidity or alkalinity

Answer

Concentration

Answer

Temperature

Answer

Density