Class 9 Practice Level 1 - Atoms and Molecules

Total questions: 40

What is the smallest particle of an element that retains the properties of that element?

Topic: Basic Concepts of Atoms and Molecules

Molecule

Atom

Compound

Mixture

None

Which of the following is a diatomic molecule?

Topic: Basic Concepts of Atoms and Molecules

$ \displaystyle {{{O}_{2}}}$

$\displaystyle {{{H}_{2}}O}$

$\displaystyle {C{{O}_{2}}}$

$ \displaystyle N{{H}_{3}}$

None

What is the chemical formula for water?

Topic: Basic Concepts of Atoms and Molecules

$\displaystyle {{{H}_{2}}{{O}_{2}}}$

$\displaystyle {{{H}_{2}}O}$

$\displaystyle {HO}$

$\displaystyle {OH}$

None

What do you call a substance made of two or more elements chemically combined in a fixed proportion?

Topic: Basic Concepts of Atoms and Molecules

Mixture

Compound

Element

Solution

None

Which scientist proposed the atomic theory in the early 19th century?

Topic: Basic Concepts of Atoms and Molecules

Isaac Newton

Albert Einstein

John Dalton

Niels Bohr

None

According to the Law of Conservation of Mass, in a chemical reaction, the mass of reactants is __________ the mass of products.

Topic: Laws of Chemical Combination

Less than

More than

Equal to

Sometimes more, sometimes less

None

Who is known as the 'Father of Modern Chemistry'?

Topic: Laws of Chemical Combination

Robert Boyle

Antoine Lavoisier

Dmitri Mendeleev

Henry Cavendish

None

What does the Law of Definite Proportions state?

Topic: Laws of Chemical Combination

A given compound always contains exactly the same proportion of elements by mass.

Elements can combine in any proportion.

The mass of products is greater than the mass of reactants

Compounds have variable compositions.

None

What is the molecular mass of water?

Topic: Molecular Mass and Mole Concept

$ \displaystyle {{{16}}{{g/mol}}}$

$ \displaystyle {{{18}}{{g/mol}}}$

$ \displaystyle {{{20}}{{g/mol}}}$

$ \displaystyle {{{22}}{{g/mol}}}$

None

10.

One mole of any substance contains how many particles?

Topic: Molecular Mass and Mole Concept

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{22}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{24}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{25}}}}$

None

11.

What are the three subatomic particles present in an atom?

Topic: Atomic Structure

Protons, neutrons, electrons

Protons, positrons, neutrons

Neutrons, positrons, electrons

Electrons, mesons, protons

None

12.

Which subatomic particle has a positive charge?

Topic: Atomic Structure

Neutron

Electron

Proton

Positron

None

13.

What do you call an atom or group of atoms that has a net electric charge?

Topic: Molecules and Ions

Isotope

Ion

Molecule

Element

None

14.

What is the charge of a proton?

Topic: Molecules and Ions

-1

None

15.

Which of the following is a polyatomic ion?

Topic: Molecules and Ions

$ \displaystyle {{Na}^{+}}$

$ \displaystyle {{Cl}^{-}}$

$ \displaystyle {{NO}^{3-}}$

$ \displaystyle {{H}^{+}}$

None

16.

What is the chemical formula for sodium chloride?

Topic: Chemical Formulas

$ \displaystyle {NaCl}$

$\displaystyle {NaC{{O}_{3}}}$

$ \displaystyle {NaOH}$

$\displaystyle {N{{a}_{2}}O}$

None

17.

How many atoms are present in one molecule of $ \displaystyle C{{O}_{2}}$?

Topic: Chemical Formulas

None

18.

What is the chemical formula for methane?

Topic: Chemical Formulas

$ \displaystyle {C{{H}_{3}}}$

$ \displaystyle {C{{H}_{4}}}$

$ \displaystyle {{{C}_{2}}{{H}_{6}}}$

$ \displaystyle {{{C}_{3}}{{H}_{8}}}$

None

19.

What is the balanced chemical equation for the reaction between hydrogen and oxygen to form water?

Topic: Stoichiometry

$ \displaystyle {H\text{ }+\text{ }O\text{ }\to \text{ }{{H}_{2}}O}$

$ \displaystyle {{{H}_{2}}+\text{ }{{O}_{2}}\to \text{ }{{H}_{2}}O}$

$ \displaystyle {{{H}_{2}}+\text{ }O\text{ }\to \text{ }{{H}_{2}}O}$

$ \displaystyle {2H2\text{ }+\text{ }{{O}_{2}}\to \text{ }2{{H}_{2}}O}$

None

20.

In the reaction $ \displaystyle {2{{\text{H}}_{\text{2}}}\text{O}\to \text{ }2{{H}_{2}}O}$, what is the mole ratio of hydrogen to water?

Topic: Stoichiometry

1:1

1:2

2:1

2:2

None

21.

What is the atomic number of an element?

Topic: Atomic Number and Mass Number

The number of neutrons in an atom

The number of electrons in an atom

The number of protons in an atom

The number of protons and neutrons in an atom

None

22.

Which element has the atomic number 1?

Topic: Atomic Number and Mass Number

Helium

Lithium

Hydrogen

Beryllium

None

23.

What is the mass number of an atom?

Topic: Atomic Number and Mass Number

The total number of protons and neutrons in the nucleus

The total number of electrons

The total number of neutrons

The total number of protons

None

24.

What are isotopes?

Topic: Isotopes

Atoms of the same element with different numbers of protons

Atoms of different elements with the same number of protons

Atoms of the same element with different numbers of neutrons

Atoms of different elements with the same number of neutrons

None

25.

Which of the following is an isotope of hydrogen?

Topic: Isotopes

Deuterium

Helium

Carbon

Oxygen

None

26.

What is the symbol for the isotope of carbon with 6 protons and 8 neutrons?

Topic: Isotopes

C-12

C-13

C-14

C-15

None

27.

What is the molar mass of carbon dioxide $ \displaystyle C{{O}_{2}}$?

Topic: Mole Concept

$ \displaystyle {{{22}}{{g/mol}}}$

$ \displaystyle {{{28}}{{g/mol}}}$

$ \displaystyle {{{44}}{{g/mol}}}$

$ \displaystyle {{{32}}{{g/mol}}}$

None

28.

How many moles are there in 22 grams of $\displaystyle C{{O}_{2}}$?

Topic: Mole Concept

0.5 moles

1 mole

2 moles

1.5 moles

None

29.

Which gas law relates the volume and amount of gas at constant temperature and pressure?

Topic: Mole Concept

Boyle's Law

Charles's Law

Avogadro's Law

Ideal Gas Law

None

30.

What is the product of the reaction between magnesium and hydrochloric acid?

Topic: Chemical Reactions and Equations

Magnesium oxide

Magnesium chloride and hydrogen gas

Magnesium hydroxide and chlorine gas

Magnesium sulphate and water

None

31.

In a chemical equation, what does the symbol (s) indicate?

Topic: Chemical Reactions and Equations

Solid

Solution

Suspension

Solute

None

32.

What is a balanced chemical equation for the combustion of methane ($ \displaystyle \text{C}{{\text{H}}_{\text{4}}}$)?

Topic: Chemical Reactions and Equations

$ \displaystyle {C{{H}_{4}}+\text{ }{{O}_{2}}\to \text{ }C{{O}_{2}}+\text{ }{{H}_{2}}O}$

$ \displaystyle {2C{{H}_{4}}+\text{ }3{{O}_{2}}\to \text{ }2C{{O}_{2}}+\text{ }2{{H}_{2}}O}$

$ \displaystyle {C{{H}_{4}}+\text{ }2{{O}_{2}}\to \text{ }C{{O}_{2}}+\text{ }2{{H}_{2}}O}$

$ \displaystyle {C{{H}_{4}}+\text{ }O\text{ }\to \text{ }C{{O}_{2}}+\text{ }{{H}_{2}}O}$

None

33.

What is Avogadro's number?

Topic: Moles and Avogadro's Number

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{22}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{24}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{25}}}}$

None

34.

How many molecules are there in 1 mole of water ($ \displaystyle {{\text{H}}_{\text{2}}}\text{O}$)?

Topic: Moles and Avogadro's Number

$\displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{22}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{24}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{25}}}}$

None

35.

How many atoms are there in 1 mole of hydrogen gas ($ \displaystyle {{\text{H}}_{\text{2}}}$)?

Topic: Moles and Avogadro's Number

$\displaystyle {12.044\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{23}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{24}}}}$

$ \displaystyle {6.022\text{ }\times \text{ }{{{10}}^{{25}}}}$

None

36.

What is the empirical formula of a compound with the molecular formula $ \displaystyle {{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}$?

Topic: Empirical and Molecular Formulas

$ \displaystyle {C{{H}_{2}}O}$

$ \displaystyle {{{C}_{2}}{{H}_{4}}{{O}_{2}}}$

$ \displaystyle {{{C}_{3}}{{H}_{6}}{{O}_{3}}}$

$\displaystyle {CHO}$

None

37.

Which of the following represents the molecular formula of a compound?

Topic: Empirical and Molecular Formulas

$ \displaystyle {C{{H}_{2}}O}$

$ \displaystyle {{{H}_{2}}O}$

$ \displaystyle {NaCl}$

$ \displaystyle {CO}$

None

38.

What is the simplest formula of a compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Topic: Empirical and Molecular Formulas

$ \displaystyle {CHO}$

$ \displaystyle {C{{H}_{2}}O}$

$ \displaystyle {{{C}_{2}}{{H}_{4}}{{O}_{2}}}$

$ \displaystyle {C{{H}_{3}}O}$

None

39.

Which element is represented by the symbol 'O'?

Topic: Periodic Table and Elements

Oxygen

Gold

Osmium

Neon

None

40.

What is the atomic number of Nitrogen?

Topic: Periodic Table and Elements

None

1 out of 40

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Class 9 Practice Level 1 - Atoms and Molecules

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