Class 9 Chemistry MCQs: Periodic Table And Periodicity Of Properties

MCQs (sample)

Showing 25 questions from this chapter. For a full timed test, use “Start online test”.

1. 1. How many valence electrons do Group 1 elements have?

   • 1
   • 2
   • 3
   • 4
   Answer & explanation

   Correct: 1

   Group 1 elements have one valence electron.

2. 2. What is the name given to the elements in group 17?

   • Halogens
   • Noble gases
   • Alkaline earth metals
   • Metalloids
   Answer & explanation

   Correct: Halogens

   The elements in group 17 are called halogens, derived from Greek words for salt and former.

3. 3. What are transition elements located in?

   • d-block of the periodic table
   • f-block of the periodic table
   • p-block of the periodic table
   • s-block of the periodic table
   Answer & explanation

   Correct: d-block of the periodic table

   Transition elements are specifically located in the d-block (Group 3 to 12) of the periodic table.

4. 4. What property allows metals to conduct heat easily?

   • High thermal conductivity
   • Low thermal conductivity
   • Brittleness
   • Low density
   Answer & explanation

   Correct: High thermal conductivity

   Metals generally have high thermal conductivity, which means they can conduct heat easily.

5. 5. What group do noble gases belong to in the periodic table?

   • Group 18
   • Group 1
   • Group 14
   • Group 7
   Answer & explanation

   Correct: Group 18

   Noble gases are found in Group 18 (or Group VIII-A) of the periodic table.

6. 6. What is the periodic trend in atomic size as you move from left to right in a period?

   • Atomic size decreases
   • Atomic size increases
   • Atomic size remains the same
   • Atomic size fluctuates
   Answer & explanation

   Correct: Atomic size decreases

   Atomic radius decreases in each period as you move across due to increased nuclear charge attracting the valence electron more strongly.

7. 7. What is the basis for the systematic arrangement of elements in the periodic table?

   • Atomic number
   • Mass number
   • Density
   • Melting point
   Answer & explanation

   Correct: Atomic number

   The periodic table is arranged based on the atomic number, which allows for a systematic organization of elements.

8. 8. What property determines how easily an element can lose electrons?

   • Metallic character
   • Atomic size
   • Density
   • Reactivity
   Answer & explanation

   Correct: Metallic character

   Metallic character refers to how easily an element can lose electrons to form cations.

9. 9. What are lanthanides also known as?

   • Rare earth elements
   • Alkaline earth metals
   • Transition metals
   • Noble gases
   Answer & explanation

   Correct: Rare earth elements

   Lanthanides are also known as 'rare earth elements'.

10. 10. What type of ion do Group 2 elements form?

    • +1 ion
    • -1 ion
    • +2 ion
    • -2 ion
    Answer & explanation

    Correct: +2 ion

    Group 2 elements tend to lose two electrons to form +2 ions.

11. 11. Which halogen exists as a pale yellow gas at room temperature and pressure?

    • Fluorine (F2)
    • Chlorine (Cl2)
    • Bromine (Br2)
    • Iodine (I2)
    Answer & explanation

    Correct: Fluorine (F2)

    Fluorine (F2) exists as a pale yellow gas at room temperature and pressure.

12. 12. Which property of transition elements is associated with their high atomic masses?

    • High Density
    • Variable Oxidation States
    • Coloured Compounds
    • Catalysts for Industrial Processes
    Answer & explanation

    Correct: High Density

    Transition elements generally possess high densities due to their higher atomic masses and closely packed structures.

13. 13. Which of the following is a characteristic of non-metals regarding electrical conductivity?

    • Good conductors due to free electrons
    • Poor conductors with few exceptions
    • Excellent conductors
    • Conductor only when in liquid form
    Answer & explanation

    Correct: Poor conductors with few exceptions

    Non-metals, with few exceptions such as graphite, are poor conductors of electricity because they lack free electrons.

14. 14. Which of the following is NOT a noble gas?

    • Krypton
    • Carbon
    • Argon
    • Neon
    Answer & explanation

    Correct: Carbon

    Carbon is not a noble gas; it is a non-metal found in Group 14.

15. 15. What effect do electrons in inner shells have on valence electrons?

    • They increase the attraction
    • They enhance the shielding effect
    • They have no effect
    • They increase ionization energy
    Answer & explanation

    Correct: They enhance the shielding effect

    Inner shell electrons reduce the force of attraction between the nucleus and the valence electrons, leading to the shielding effect.

16. 16. How many periods are there in the periodic table?

    • 7
    • 8
    • 6
    • 5
    Answer & explanation

    Correct: 7

    There are seven periods in the periodic table.

17. 17. How does metallic character change as you move down a group in the periodic table?

    • Increases
    • Decreases
    • Remains constant
    • Varies randomly
    Answer & explanation

    Correct: Increases

    Metallic character increases down a group due to the addition of new electronic shells.

18. 18. How many elements are in the lanthanide series?

    • 14
    • 12
    • 16
    • 10
    Answer & explanation

    Correct: 14

    There are 14 elements in the lanthanide series.

19. 19. Which of the following elements would likely form a -1 ion?

    • Oxygen
    • Chlorine
    • Beryllium
    • Sodium
    Answer & explanation

    Correct: Chlorine

    Chlorine, a Group 17 element, gains one electron to form a -1 ion.

20. 20. What trend in color do halogens exhibit as you move down the group?

    • Colors become lighter
    • Colors remain unchanged
    • Colors become darker
    • Colors become brighter
    Answer & explanation

    Correct: Colors become darker

    Halogen colors become darker as you go down the group.

21. 21. Why do transition elements have high melting points?

    • Low atomic mass
    • Strong metallic bonding
    • Weak d-sub shell participation
    • High electronegativity
    Answer & explanation

    Correct: Strong metallic bonding

    Transition elements have high melting points because their metallic bonding is stronger due to the presence of partially filled d-sub shells.

22. 22. What is a defining feature of metals related to their malleability?

    • Brittle structure
    • Ductile and malleable
    • High gaseous state
    • Poor electrical conductivity
    Answer & explanation

    Correct: Ductile and malleable

    Metals are malleable and ductile, which means they can be hammered and drawn into wires without breaking.

23. 23. What is the general electron configuration of noble gases, except for Helium?

    • ns² np⁶
    • ns²
    • 1s² 2s² 2p⁶
    • n²
    Answer & explanation

    Correct: ns² np⁶

    Noble gases have a general electron configuration of ns² np⁶, except for Helium which has 1s².

24. 24. How does the ionization energy change as you move down a group?

    • It increases
    • It decreases
    • It remains the same
    • It fluctuates
    Answer & explanation

    Correct: It decreases

    The ionization energy decreases from top to bottom in a group due to increased shielding effect which weakens attraction between the nucleus and valence electrons.

25. 25. What are the first three periods of the periodic table called?

    • Short periods
    • Long periods
    • Nested periods
    • Compact periods
    Answer & explanation

    Correct: Short periods

    The first three periods of the periodic table are referred to as short periods.