Chemistry 9th Chap 3 : Topic 13 - Maryam Publications

Chemistry Chapter 3 : Topic 13

Isotope Composition

1 / 20

A student is given three isotopes of the same element: 612C, 613C, and 614C. He is asked which statement correctly describes their nuclear composition.

A) All isotopes have different numbers of protons but same neutrons

B) All isotopes have same number of protons but different neutrons

C) Both protons and neutrons are different in all isotopes

D) All isotopes have same number of neutrons but different protons

2 / 20

A nucleus is represented as 11 23 Na. A student concludes that the number of neutrons is obtained by subtracting atomic number from mass number.

A) 23 neutrons

B) 34 neutrons

C) 12 neutrons

D) 11 neutrons

3 / 20

An isotope is written as 17 35 Cl. If another isotope of chlorine is 17 35 Cl, what change occurs between the two atoms?

A) Both protons and neutrons change

B) Neutrons increase by 2

C) Protons increase by 2

D) Electrons decrease by 2

4 / 20

A chemist compares 20 40 Ca and 20 44 Ca. He observes a difference in stability. What is the reason?

A) Different number of neutrons

B) Different number of electrons

C) Different number of protons

D) Different atomic numbers

5 / 20

If an atom has atomic number 15 and mass number 31, what is true about it?

A) It has 46 neutrons

B) It has 15 neutrons

C) It has 16 neutrons

D) It has 31 neutrons

6 / 20

A student says isotopes of hydrogen ( 1H, 2H, 3H) differ only in neutrons. What conclusion is correct?

A) All isotopes have same mass number

B) All isotopes have same neutron number

C) All isotopes have same proton number

D) All isotopes have different atomic numbers

7 / 20

An isotope of oxygen is represented as 8 18 O. How many neutrons does it contain?

A) 18

B) 26

C) 10

D) 8

8 / 20

Which statement best explains why isotopes have similar chemical properties?

A) Same number of electrons and protons

B) Same number of neutrons

C) Same neutron-to-proton ratio

D) Same mass number

9 / 20

A nucleus contains 17 protons and 20 neutrons. Its correct notation is:

A) 17 35 Cl

B) 10 37 Ar

C) 18 35 Ar

D) 17 37 Cl

10 / 20

Which pair represents isotopes of the same element?

A) 17 35 Cl and 17 37 Cl

B) 6 12 C and 5 12 B

C) 11 23 Na and 12 24 Mg

D) 6 14 C and 7 14 N

11 / 20

A student calculates neutrons incorrectly by subtracting mass number from atomic number. What result is expected for 20 40 Ca?

A) 40

B) 60

C) - 20

D) 20

12 / 20

Which of the following changes when comparing isotopes of chlorine?

A) Number of electrons only

B) Both protons and neutrons

C) Number of protons only

D) Number of neutrons only

13 / 20

An element has isotopes 6 12 X and 6 14 X. What is constant in both?

A) Neutron number

B) Mass number

C) Atomic mass

D) Proton number

14 / 20

A nucleus has 8 protons and 9 neutrons. What is its mass number?

A) 8

B) 1

C) 9

D) 17

15 / 20

Which statement correctly defines isotopes?

A) Atoms with same neutrons but different protons

B) Atoms with same mass number but different electrons

C) Atoms with different atomic numbers

D) Atoms with same protons but different neutrons

16 / 20

A student compares 12 24 Mg and 12 25 Mg. What is the difference?

A) 1 neutron

B) 1 atomic number

C) 1 electron

D) 1 proton

17 / 20

If an isotope has mass number 56 and 30 neutrons, its atomic number is:

A) 26

B) 56

C) 86

D) 30

18 / 20

Why do isotopes of the same element behave similarly in chemical reactions?

A) Same number of electrons

B) Same nuclear stability

C) Same neutrons

D) Same mass number

19 / 20

A nucleus is written as 21 45 Sc. Number of neutrons is:

A) 21

B) 45

C) 66

D) 24

20 / 20

Which observation confirms isotopes experimentally?

A) Same neutron number

B) Same melting point

C) Same physical state

D) Same atomic number but different mass number

Your score is

0%