Structure of the atom Worksheet-2

Structure of the atom Worksheet-2

11. The nucleus of an atom consists of ______.

A. Protons                                      B. Electrons and neutrons

C. Protons and neutrons             D. Neutrons

12. Alpha particles are _____ particles.

A. Negatively charged                 B. Positively charged

C. Neutral                                     

13. The certain species A' has 9 protons and 8 electrons. What is it?

A. Cation            B. Anion             C. Atom

14. Who discovered neutrons?

A. J. J. Thomson

B. E. Goldstein

C. James Chadwick

15. What is the maximum number of electrons which can be present in K and L shells in an atom ?

A. 2 and 8          B. 2 and 18        C. 2 and 32        D. 8 and 18

16. There are 14 protons and 13 neutrons in the nucleus of an element. What is its mass number?

A. 14                    B. 13                    C. 27

17. Indicate the number of electrons, protons and neutrons in the given element ₁₉K³⁹.

A. 19 electrons, 19 protons and 20 neutrons

B. 19 electrons, 20 protons and 19 neutrons

C. 20 electrons, 19 protons and 19 neutrons

18. What is common in the isotopes of an element?

A. Mass number

B. Atomic number

C. Number of neutrons

19. From the following nuclei, choose the isotopes and isobars:

(i) 8p + 8n (ii) 19p + 21n (iii) 8p +10n (iv) 20p + 20n.

A. (i)and (iii) isotopes , (ii)and (iv) isobars

B. (i)and (iv) isotopes , (ii)and (iii) isobars

C. (ii)and (iii) isotopes , (ii)and (iv) isobars

D. (iv)and (iii) isotopes , (ii)and (i) isobars

20. Name the radioisotope used in cancer therapy.

A. I-131               B. Cu-64            C. Bi-213            D. Co-60

Answer:

11. C

Explanation: The nucleus of an atom consists of neutrons and protons.

12. B

Explanation: Alpha particles are made up of two protons and two neutrons hence these are positively charged particles.

13. A

Explanation: It has one unit positive charge (A+). The number of protons is more than the number of electrons.

14. C

15. A

Explanation: K and L shells of an atom can have maximum 2 and 8 electrons.

16. C

Explanation: Mass number is sum of number of protons and neutrons in an atom.

14 + 13 = 27

17. A

Explanation: Electrons = 19; protons = 19; neutrons = 20.

18. B

Explanation: Isotopes of an element have same atomic number.

19. A

Explanation: Atoms of an element having same atomic number but different mass number are called isotopes.

Atoms of different elements having same mass numbers (same number of nucleons) but different atomic numbers are called isobars.

20. D