On account of the disruption in education due to the corona pandemic, we're opening up our platform for teachers, free of cost. Know More →

Class 9

Explore popular questions from Atoms and Molecules for Class 9. This collection covers Atoms and Molecules previous year Class 9 questions hand picked by experienced teachers.

Atoms and Molecules

Correct Marks 4

Incorrectly Marks -1

Q 1. Kanad gave which theory

A

Atomic theory

Electronic theory

C

Parmanu theory

D

Oxide theory

Correct Marks 4

Incorrectly Marks -1

Q 2. An atom has

A

Proton inside the nucleus whereas electrons and neutrons outside the nucleus

Proton and neutron inside the nucleus and electrons outside the nucleus

C

electrons inside the nucleus

D

none of these

Correct Marks 4

Incorrectly Marks -1

Q 3. Valency electrons refers to the

electrons of the outermost shell

B

total electrons in an atom

C

electrons of the inner shells

D

none of these

Correct Marks 4

Incorrectly Marks -1

Q 4. Which of the following is a monoatomic molecule ?

A

HCl

B

CO{tex}_2{/tex}

C

NH{tex}_3{/tex}

He

Correct Marks 4

Incorrectly Marks -1

Q 5. When an electron from an outermost shell of an atom is removed than what happens?

a cation is formed

B

an anion is formed

C

a neutral species is formed

D

no change is noticed

Correct Marks 4

Incorrectly Marks -1

Q 6. Na{tex}^+{/tex}, Mg{tex}^{2+}{/tex} are actually

cations

B

anions

C

neutral species

D

Na{tex}^+{/tex} is a cation

Correct Marks 4

Incorrectly Marks -1

Q 7. "During a chemical reaction matter is neither created nor destroyed". The above statement is according to

Law of conservation of mass

B

Law of constant proportions

C

Avogadro law

D

None of these

Correct Marks 4

Incorrectly Marks -1

Q 8. A molecule is defined as a

the smallest particle of an element or of a compound which can exist freely under ordinary conditions and shows all the properties of that substance

B

smallest particle of an element

C

the charged species obtained by the loss or gain of electron from an atom

D

any uncharged species

Correct Marks 4

Incorrectly Marks -1

Q 9. If the molecular mass of H{tex}_2{/tex}O is 18 grams and that of hydrogen is 1g the molecular mass of oxygen is

16 g

B

17 g

C

16.5 g

D

18 g

Correct Marks 4

Incorrectly Marks -1

Q 10. Which of the following is a pair of atoms?

A

H{tex}_{2}{/tex} and O{tex}_{2}{/tex}

B

NH{tex}_3{/tex} and C

C

N{tex}_{2}{/tex} and Xe

He and C

Correct Marks 4

Incorrectly Marks -1

Q 11. One 'u' stands for:

A

An atom of carbon (C-12)

{tex}\frac{1}{12}{/tex}th of carbon atom (C-12)

C

{tex}\frac{1}{12}{/tex}th of hydrogen atoms

D

one atom of all the elements

Correct Marks 4

Incorrectly Marks -1

Q 12. The no of oxygen atoms in 4.4 g of CO{tex}_2{/tex} is approx

A

6 x 10{tex}^{22}{/tex}

B

6 x 10{tex}^{23}{/tex}

C

12 x 10{tex}^{23}{/tex}

1.2 x 10{tex}^{23}{/tex}

Correct Marks 4

Incorrectly Marks -1

Q 13. Which has maximum number of molecules?

A

1 g of CO{tex}_2{/tex}

B

1 g of N{tex}_{2}{/tex}

1g of H{tex}_{2}{/tex}

D

1 g of CH{tex}_{4}{/tex}

Correct Marks 4

Incorrectly Marks -1

Q 14. The law of constant composition is applied to

A

Any element

B

Any chemical compound

Pure chemical compound

D

None of these

Correct Marks 4

Incorrectly Marks -1

Q 15. What mass of carbon dioxide (CO{tex}_2{/tex}) will contain 3.011 x 10{tex}^{23}{/tex} molecules?

A

11.0 g

22.0 g

C

4.4 g

D

44.0 g

Correct Marks 4

Incorrectly Marks -1

Q 16. The value of Avogadro's constant is:

A

6.0 x 10{tex}^{24}{/tex}

B

6.01 x 10{tex}^{22}{/tex}

6.023 x 10{tex}^{23}{/tex}

D

6.023 x 10{tex}^{-23}{/tex}

Correct Marks 4

Incorrectly Marks -1

Q 17. The law of constant proportion was proposed by

A

Dalton

B

Avogadro

Joseph Proust

D

A Lavoisier

Correct Marks 4

Incorrectly Marks -1

Q 18. The best standard for atomic mass is

carbon - 12

B

oxygen - 16

C

hydrogen - 1

D

chlorine - 35

Correct Marks 4

Incorrectly Marks -1

Q 19. One amu is

A

1.00758 g

B

0.000549 g

1.66 x 10{tex}^{-24}{/tex} g

D

6.023 x 10{tex}^{-23}{/tex} g

Correct Marks 4

Incorrectly Marks -1

Q 20. The percentage of hydrogen in water is

A

1.11%

11.11%

C

8.89%

D

88.9%

Correct Marks 4

Incorrectly Marks -1

Q 21. The atom is indivisible was proposed by

A

Einstein

B

Lavoisier

Dalton

D

Proust

Correct Marks 4

Incorrectly Marks -1

Q 22. The percentage of calcium in CaCO{tex}_3{/tex} is

40%

B

12%

C

48%

D

none of these

Correct Marks 4

Incorrectly Marks -1

Q 23. {tex}\mathrm{Assertion}{/tex} : Gram atomic mass of an element contains Avogadro's number of atoms
{tex}\mathrm{Reason}{/tex} : amu is called atomic mass unit

A

Both Assertion and Reason are true and Reason is the correct explanation of 'Assertion'

Both Assertion and Reason are true and Reason is not the correct explanation of 'Assertion'

C

Assertion is true but Reason is false

D

Assertion is false but Reason is true

Correct Marks 4

Incorrectly Marks -1

Q 24. {tex}\mathrm{Assertion}{/tex} : It is not possible to seen an atom with naked eyes
{tex}\mathrm{Reason}{/tex} : It is very small in size

Both Assertion and Reason are true and Reason is the correct explanation of 'Assertion'

B

Both Assertion and Reason are true and Reason is not the correct explanation of 'Assertion'

C

Assertion is true but Reason is false

D

Assertion is false but Reason is true

Correct Marks 4

Incorrectly Marks -1

Q 25. {tex}\mathrm{Assertion}{/tex} : Atomic radius is expressed in 'nanometres'
{tex}\mathrm{Reason}{/tex} : 1 nm = 10{tex}^{-9}{/tex} m

A

Both Assertion and Reason are true and Reason is the correct explanation of 'Assertion'

Both Assertion and Reason are true and Reason is not the correct explanation of 'Assertion'

C

Assertion is true but Reason is false

D

Assertion is false but Reason is true