chemistry MCQs - 9th class Chapter 04 Mcqs

1

Stoichiometry is based on which fundamental law?

A

Law of Definite Proportions

B

Law of Multiple Proportions

C

Law of Conservation of Mass

D

Avogadro's Law

2

The stoichiometric coefficient in a balanced chemical equation provides the what?

A

Mass ratio

B

Mole ratio

C

Volume ratio

D

Particle size ratio

3

Which of the following exists as discrete molecules where atoms are chemically bonded?

A

Sodium (Na)

B

Iron (Fe)

C

Calcium (Ca)

D

Ozone (O3)

4

Sodium chloride (NaCl) is an ionic compound that exists in the form of a what?

A

Discrete molecule

B

Crystal

C

Gas

D

Liquid

5

Which of these is an example of a covalent compound?

A

KCl

B

BaCl2

C

H2O

D

NaCl

6

What does the empirical formula of a compound represent?

A

The actual number of atoms

B

The arrangement of atoms

C

The simplest whole number ratio of atoms

D

The total mass of atoms

7

What is the empirical formula of benzene (C6H6)?

A

C2H2

B

C3H3

C

CH

D

C6H6

8

Which compound has the same molecular and empirical formula?

A

Hydrogen peroxide (H2O2)

B

Benzene (C6H6)

C

Acetylene (C2H2)

D

Water (H2O)

9

Which method is used to write the formula of a binary ionic compound from its ions?

A

Titration method

B

Criss-cross method

C

Spectroscopy method

D

Distillation method

10

What is the correct chemical formula for aluminium oxide?

A

AlO

B

Al2O

C

AlO2

D

Al2O3

11

Using the criss-cross method, what is the formula for magnesium nitride (Mg²⁺ and N³⁻)?

A

MgN

B

Mg2N3

C

Mg3N2

D

MgN2

12

According to Table 4.1, what is the charge on a potassium (K) ion?

A

+1

B

+2

C

-1

D

-2

13

According to Table 4.1, what are the possible charges for an iron (Fe) ion?

A

Fe¹⁺, Fe²⁺

B

Fe²⁺, Fe³⁺

C

Fe¹⁺, Fe³⁺

D

Fe³⁺, Fe⁴⁺

14

In the equation, Molecular formula = n × (Empirical Formula), 'n' is the ratio of Molar Mass to what?

A

Atomic Mass

B

Molecular Mass

C

Empirical Formula Mass

D

Ionic Mass

15

If the value of 'n' in the molecular formula calculation is 1, what is the relationship between molecular and empirical formulas?

A

Molecular formula is half the empirical formula

B

They are unrelated

C

They are identical

D

Molecular formula is double the empirical formula

16

What is the value of Avogadro's number (NA)?

A

6.022 x 10²²

B

6.022 x 10²³

C

6.022 x 10²⁴

D

3.011 x 10²³

17

The mass of one mole of a substance is called its what?

A

Atomic mass

B

Formula mass

C

Molar mass

D

Relative mass

18

What is the molar mass of carbon (C) atoms?

A

6 g/mol

B

12 g/mol

C

14 g/mol

D

24 g/mol

19

In a chemical equation, reactants are conventionally written on which side?

A

Right-hand side

B

Above the arrow

C

Below the arrow

D

Left-hand side

20

What does the symbol (aq) signify in a chemical equation?

A

The substance is a gas

B

The substance is a solid

C

The substance is dissolved in water

D

The substance is a liquid

21

A reaction that can proceed in both forward and reverse directions is called a what?

A

Complete reaction

B

Precipitation reaction

C

Neutralization reaction

D

Reversible reaction

22

What is the molar mass of H₂SO₄?

A

49 g/mol

B

98 g/mol

C

100 g/mol

D

196 g/mol

23

In the reaction 2H₂ + O₂ → 2H₂O, how many moles of hydrogen react with one mole of oxygen?

A

1 mole

B

2 moles

C

0.5 moles

D

4 moles

24

Which of the following statements about ionic compounds is true according to the text?

A

They exist as discrete molecules

B

They are always covalent

C

They are represented by their empirical formulas

D

They do not conduct electricity

25

Both benzene (C₆H₆) and acetylene (C₂H₂) have the same what?

A

Molecular formula

B

Molar mass

C

Empirical formula

D

Number of atoms

26

What is the charge on an oxide anion (O)?

A

1-

B

2-

C

1+

D

2+

27

The chemical formula for ammonia is given in the text as:

A

NH4

B

NO2

C

NH3

D

N2H4

28

What separates the reactants from the products in a written chemical equation?

A

A plus sign (+)

B

A double-headed arrow (↔)

C

An arrow (→)

D

An equals sign (=)

29

What is the mole ratio of CaCO₃ to HCl in the reaction: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂?

A

1:1

B

2:1

C

1:2

D

1:3

30

According to the text, 1.00 g is equal to how many amu?

A

1.66 x 10⁻²⁴ amu

B

1 amu

C

6.022 x 10²³ amu

D

100 amu

31

Avogadro's number is named after which Italian scientist?

A

Galileo Galilei

B

Alessandro Volta

C

Amedeo Avogadro

D

Enrico Fermi

32

What is the chemical formula for methane gas mentioned in the text?

A

C2H6

B

CH4

C

C2H4

D

CH3OH

33

To deduce the molecular formula from a structural formula, what is the first step?

A

Write the symbols of all elements

B

Count the number of atoms of each type

C

Write down the structural formula

D

Remove the subscript 1

34

The amount of substance containing Avogadro's number of particles is defined as a what?

A

Gram

B

Mole

C

Dozen

D

Kilogram

35

The total mass of all reactants must be equal to the total mass of all the what?

A

Products

B

Catalysts

C

Solvents

D

Gases produced

36

What is the empirical formula of hydrogen peroxide (H₂O₂)?

A

H2O

B

HO2

C

H2O2

D

HO

37

Which element's symbol is simply 'C'?

A

Calcium

B

Chlorine

C

Carbon

D

Copper

38

What is the ratio of ions in a formula unit of CaCl₂?

A

1:1

B

2:1

C

1:2

D

2:2

39

In the reaction 4Al + 3O₂ → 2Al₂O₃, what are the reactants?

A

Al and Al₂O₃

B

O₂ and Al₂O₃

C

Al and O₂

D

Only Al₂O₃

40

If the empirical formula of a compound is CH₂O and its molar mass is 180 g/mol, what is the value of 'n'?

A

2

B

4

C

6

D

8

41

The molar mass of oxygen molecules (O₂) is:

A

8 g/mol

B

16 g/mol

C

32 g/mol

D

64 g/mol

42

A chemical equation must obey the law of conservation of what?

A

Energy

B

Momentum

C

Charge

D

Mass

43

The symbol for a liquid physical state in a chemical equation is:

A

(g)

B

(s)

C

(aq)

D

(l)

44

In the sample problem, the molar mass of benzene (C₆H₆) is given as:

A

13 g/mol

B

78 g/mol

C

90 g/mol

D

100 g/mol

45

The molecular formula of acetic acid is given as C₂H₄O₂. How many oxygen atoms does it have?

A

1

B

2

C

4

D

6

46

A mole of sodium chloride (NaCl) consists of 6.022 x 10²³ of its what?

A

Atoms

B

Molecules

C

Formula units

D

Ions

47

The reaction to produce urea fertilizer involves ammonia and what other reactant?

A

Oxygen

B

Water

C

Carbon dioxide

D

Nitrogen

48

What is the mass of 2 moles of carbon atoms?

A

12 g

B

6 g

C

24 g

D

18 g

49

The process of calculating amounts of reactants and products from a balanced equation is called what?

A

Titration

B

Stoichiometry

C

Calorimetry

D

Spectrometry