SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions | Assam Eduverse
SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions are prepared to help students understand the development of the periodic table and modern periodic law for the HSLC examination. These SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions include theory-based questions, reasoning questions, previous year questions (PYQs), and important MCQs.
The SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions strictly follow the latest SEBA (ASSEB) syllabus for 2026–27. Since the HSLC exam requires students to attempt 45 MCQs, practising MCQs from SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions is essential.
Topics covered in SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions include Mendeleev’s periodic table, modern periodic law, periodic trends, valency, atomic size, metallic and non-metallic properties. Students searching for HSLC Science Chapter 5 Periodic Classification of Elements Important Questions or SEBA Class 10 Science Chapter 5 PYQs will find this resource highly beneficial.
SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Questions with PYQs and MCQs
Table of Contents
A. Previous Year Questions with Answers
Q1. In the periodic table of the elements, in a period from left to right atomic radius gradually — [HSLC ’16]
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Answer: (b) decreases
Q2. An atom has electronic configuration 2,8,7. To which of the following elements would it be chemically similar? [HSLC ’17]
(a) N (7)
(b) F (9)
(c) P (15)
(d) Ar (18)
Answer: (b) F (9)
Q3. Which of the following is not a correct statement about the trends when going from left to right across the periods of the periodic table? [HSLC ’18]
(a) The elements become less metallic in nature
(b) The number of valence electrons increases
(c) Elements lose their valence electrons more easily
(d) The oxides become more acidic
Answer: (c) Elements lose their valence electrons more easily
Q4. An element X forms a chloride with the formula XCl, which is a solid with high melting point. X would most likely be in the same group of the Periodic Table as — [HSLC ’19]
(a) Na
(b) Mg
(c) Al
(d) Si
Answer: (a) Na
Q5. Using Mendeleev’s Periodic Table the formula predicted for the oxide of element ‘K’ is — [HSLC ’22]
(a) KO₂
(b) K₂O
(c) K₂O₃
(d) K₂O₂
Answer: (b) K₂O
Q6. Which of the following is not an example of metalloid? [HSLC ’23]
(a) Si
(b) Ge
(c) B
(d) Al
Answer: (d) Al
Q7. In the Periodic Table, which of the following properties increase from top to bottom in a group? [HSLC 2024]
(i) Valency
(ii) Metallic character
(iii) Effective nuclear charge
(iv) Atomic radius
(A) (i) and (ii)
(B) (ii) and (iv)
(C) (iii) and (iv)
(D) (i) and (iv)
Answer: (B) (ii) and (iv)
Q8. Element X forms a chloride with the formula XCl₂, which is a solid with high melting point. X would most likely be in same group of the Periodic Table as [HSLC 2024]
(A) Na
(B) Mg
(C) Al
(D) Si
Answer: (B) Mg
Q9. By considering their position in the periodic table, which one of the following elements would you expect to have maximum metallic characteristic? [HSLC 2025]
(a) Ga
(b) Ge
(c) As
(d) Se
Answer: (a) Ga
Q10. Boron is a non-metal and is placed under group 13 and period 2 of the periodic table. How can boron form bonds with other elements? [HSLC 2025]
(a) By sharing 5 electrons
(b) By sharing 3 electrons
(c) By sharing 2 electrons
(d) By sharing 1 electron
Answer: (b) By sharing 3 electrons
Q11. What is the trend of valency along the periods in the modern periodic table? [HSLC 2025]
(a) It increases from left to right
(b) It decreases from right to left
(c) It increases and then decreases
(d) It decreases and then increases
Answer: (c) It increases and then decreases
B. Extra Questions with Answers
Q.1. Döbereiner arranged lithium (6.9), sodium (23.0) and potassium (39.0) in a triad. What is the relation between their atomic masses?
(i) Atomic mass of Na is the average of Li and K
(ii) Atomic mass of K is the average of Li and Na
(iii) Atomic mass of Li is the average of Na and K
(iv) There is no relation
Answer: (i) Atomic mass of Na is the average of Li and K
Q.2. Which of the following groups form Döbereiner’s triads?
Group A: N (14.0), P (31.0), As (74.9)
Group B: Ca (40.1), Sr (87.6), Ba (137.3)
Group C: Cl (35.5), Br (79.9), I (126.9)
(i) Only Group A
(ii) Only Group B
(iii) Group B and Group C
(iv) All A, B and C
Answer: (iii) Group B and Group C
Q.3. According to Newlands’ Law of Octaves, every eighth element has properties similar to the first when elements are arranged in order of —
(i) Increasing atomic number
(ii) Increasing atomic mass
(iii) Decreasing atomic mass
(iv) Increasing valency
Answer: (ii) Increasing atomic mass
Q.4. Assertion (A): Newlands’ Law of Octaves was applicable only up to calcium.
Reason (R): After calcium, every eighth element did not possess properties similar to that of the first.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.5. Mendeléev arranged elements in his Periodic Table on the basis of —
(i) Increasing atomic number
(ii) Increasing atomic mass and similarity in chemical properties
(iii) Increasing valency
(iv) Increasing density
Answer: (ii) Increasing atomic mass and similarity in chemical properties
Q.6. Mendeléev predicted the existence of some undiscovered elements and named them by prefixing —
(i) Latin numerals
(ii) Greek numerals
(iii) Sanskrit numeral ‘Eka’
(iv) Roman numerals
Answer: (iii) Sanskrit numeral ‘Eka’
Q.7. Match the following elements predicted by Mendeléev with the elements discovered later:
A. Eka–aluminium
B. Eka–boron
C. Eka–silicon
Scandium
Gallium
Germanium
(i) A–2, B–1, C–3
(ii) A–1, B–2, C–3
(iii) A–3, B–2, C–1
(iv) A–2, B–3, C–1
Answer: (i) A–2, B–1, C–3
Q.8. Assertion (A): Hydrogen does not have a fixed position in Mendeléev’s Periodic Table.
Reason (R): Hydrogen resembles both alkali metals and halogens.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.9. According to the Modern Periodic Law, the properties of elements are periodic function of their —
(i) Atomic mass
(ii) Valency
(iii) Atomic number
(iv) Density
Answer: (iii) Atomic number
Q.10. An element has electronic configuration 2, 8, 1. In which group and period of the Modern Periodic Table will it be placed?
(i) Group 1, Period 3
(ii) Group 3, Period 1
(iii) Group 8, Period 2
(iv) Group 2, Period 3
Answer: (i) Group 1, Period 3
Q.11. The maximum number of electrons that can be accommodated in the L shell is —
(i) 2
(ii) 8
(iii) 18
(iv) 32
Answer: (ii) 8
Q.12. The first period of the Modern Periodic Table contains only two elements because —
(i) K shell can accommodate maximum 2 electrons
(ii) L shell can accommodate 2 electrons
(iii) M shell can accommodate 8 electrons
(iv) Valency of elements is 2
Answer: (i) K shell can accommodate maximum 2 electrons
Q.13. Assertion (A): Elements in the same group of the Modern Periodic Table have similar chemical properties.
Reason (R): They have the same number of valence electrons in their outermost shell.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.14. In the second period, the number of elements is —
(i) 2
(ii) 8
(iii) 18
(iv) 32
Answer: (ii) 8
Q.15. Arrange the following elements of the second period in decreasing order of their atomic radii: Be (111 pm), B (88 pm), C (77 pm), N (74 pm), O (66 pm).
(i) Be > B > C > N > O
(ii) O > N > C > B > Be
(iii) B > Be > C > N > O
(iv) Be > C > B > N > O
Answer: (i) Be > B > C > N > O
Q.16. Assertion (A): Atomic size decreases from left to right in a period.
Reason (R): Nuclear charge increases and pulls electrons closer to the nucleus.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.17. As we move down a group in the Modern Periodic Table, atomic size —
(i) Decreases
(ii) Increases
(iii) Remains same
(iv) First increases then decreases
Answer: (ii) Increases
Q.18. The valency of magnesium (atomic number 12) is —
(i) 1
(ii) 2
(iii) 3
(iv) 6
Answer: (ii) 2
Q.19. Match the following:
A. Group 1 elements
B. Group 17 elements
C. Group 18 elements
- Noble gases
- Halogens
- Alkali metals
(i) A–3, B–2, C–1
(ii) A–2, B–3, C–1
(iii) A–1, B–2, C–3
(iv) A–3, B–1, C–2
Answer: (i) A–3, B–2, C–1
Q.20. Metallic character of elements —
(i) Increases across a period and decreases down a group
(ii) Decreases across a period and increases down a group
(iii) Remains same across a period
(iv) Decreases both across a period and down a group
Answer: (ii) Decreases across a period and increases down a group
Q.21. Assertion (A): Non-metals are electronegative in nature.
Reason (R): They tend to form bonds by gaining electrons.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.22. How does the tendency to lose electrons change as we move from left to right in a period?
(i) Increases
(ii) Decreases
(iii) Remains same
(iv) First increases then decreases
Answer: (ii) Decreases
Q.23. In the Modern Periodic Table, metals are generally found —
(i) On the right-hand side
(ii) In the middle only
(iii) On the left-hand side
(iv) At the bottom only
Answer: (iii) On the left-hand side
Q.24. The elements boron, silicon, germanium, arsenic, antimony, tellurium and polonium are called —
(i) Alkali metals
(ii) Halogens
(iii) Noble gases
(iv) Metalloids
Answer: (iv) Metalloids
Q.25. Arrange the following Group 1 elements in increasing order of their atomic radii: Li (152 pm), Na (186 pm), K (231 pm), Rb (244 pm), Cs (262 pm).
(i) Cs < Rb < K < Na < Li
(ii) Li < Na < K < Rb < Cs
(iii) Na < Li < K < Rb < Cs
(iv) Li < K < Na < Rb < Cs
Answer: (ii) Li < Na < K < Rb < Cs
Q.26. Assertion (A): Down a group, metallic character increases.
Reason (R): The effective nuclear charge experienced by valence electrons decreases down the group.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.27. The number of groups and periods in the Modern Periodic Table are respectively —
(i) 7 groups and 18 periods
(ii) 8 groups and 7 periods
(iii) 18 groups and 7 periods
(iv) 7 groups and 8 periods
Answer: (iii) 18 groups and 7 periods
Q.28. In a period, the number of valence electrons —
(i) Decreases from left to right
(ii) Increases from left to right
(iii) Remains constant
(iv) First increases then decreases
Answer: (ii) Increases from left to right
Q.29. Match the following regarding trends in a period:
A. Atomic size
B. Metallic character
C. Tendency to gain electrons
- Increases
- Decreases
- Increases from left to right
(i) A–2, B–2, C–3
(ii) A–1, B–2, C–3
(iii) A–2, B–1, C–3
(iv) A–3, B–2, C–1
Answer: (i) A–2, B–2, C–3
Q.30. The element in the third period having completely filled outermost shell is —
(i) Na
(ii) Mg
(iii) Cl
(iv) Ar
Answer: (iv) Ar
Q.31. In the Modern Periodic Table, elements having the same number of occupied shells are placed in the same —
(i) Group
(ii) Period
(iii) Block
(iv) Series
Answer: (ii) Period
Q.32. The maximum number of electrons that can be accommodated in the M shell according to the formula 2n² is —
(i) 8
(ii) 18
(iii) 32
(iv) 2
Answer: (ii) 18
Q.33. Assertion (A): The third period contains only 8 elements.
Reason (R): Though the M shell can accommodate 18 electrons, the outermost shell can have only 8 electrons.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.34. An element has electronic configuration 2, 8, 7. Its valency is —
(i) 1
(ii) 2
(iii) 7
(iv) 8
Answer: (i) 1
Q.35. Which of the following pairs of elements belong to the same group and hence show similar chemical properties?
(i) Na and Mg
(ii) Cl and Ar
(iii) Li and Na
(iv) C and O
Answer: (iii) Li and Na
Q.36. Match the following elements with their groups in the Modern Periodic Table:
A. Fluorine
B. Sodium
C. Neon
- Group 1
- Group 17
- Group 18
(i) A–2, B–1, C–3
(ii) A–1, B–2, C–3
(iii) A–3, B–1, C–2
(iv) A–2, B–3, C–1
Answer: (i) A–2, B–1, C–3
Q.37. As we move down a group, the number of shells in the atoms —
(i) Decreases
(ii) Remains same
(iii) Increases
(iv) First decreases then increases
Answer: (iii) Increases
Q.38. Assertion (A): Oxides of metals are generally basic in nature.
Reason (R): Metals tend to lose electrons and form positive ions.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.39. In the Modern Periodic Table, the tendency to gain electrons across a period from left to right —
(i) Decreases
(ii) Increases
(iii) Remains constant
(iv) First decreases then increases
Answer: (ii) Increases
Q.40. Which of the following statements correctly explains why elements in the same group have similar chemical properties?
(i) They have the same atomic number
(ii) They have the same number of valence electrons
(iii) They have the same number of shells
(iv) They have the same atomic mass
Answer: (ii) They have the same number of valence electrons
Q.41. Which of the following elements of the third period is a metalloid?
(i) Na
(ii) Mg
(iii) Si
(iv) Cl
Answer: (iii) Si
Q.42. Assertion (A): Atomic size increases down a group.
Reason (R): New shells are added as we move down the group, increasing the distance between the nucleus and outermost electrons.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.43. In Mendeléev’s Periodic Table, vertical columns are called —
(i) Periods
(ii) Groups
(iii) Shells
(iv) Series
Answer: (ii) Groups
Q.44. In the Modern Periodic Table, horizontal rows are known as —
(i) Groups
(ii) Blocks
(iii) Periods
(iv) Series
Answer: (iii) Periods
Q.45. Which of the following noble gases were placed in a new group without disturbing the existing order of Mendeléev’s Periodic Table?
(i) Helium, Neon, Argon
(ii) Hydrogen, Oxygen, Nitrogen
(iii) Lithium, Sodium, Potassium
(iv) Fluorine, Chlorine, Bromine
Answer: (i) Helium, Neon, Argon
Q.46. Match the following scientists with their contributions:
A. Döbereiner
B. Newlands
C. Mendeléev
- Law of Octaves
- Periodic Table based on atomic mass
- Triads
(i) A–3, B–1, C–2
(ii) A–1, B–3, C–2
(iii) A–2, B–1, C–3
(iv) A–3, B–2, C–1
Answer: (i) A–3, B–1, C–2
Q.47. Which of the following statements about isotopes is correct?
(i) They have different chemical properties and same atomic mass
(ii) They have same chemical properties but different atomic masses
(iii) They have same atomic mass and different atomic numbers
(iv) They have different atomic numbers and different chemical properties
Answer: (ii) They have same chemical properties but different atomic masses
Q.48. Assertion (A): Isotopes posed a challenge to Mendeléev’s Periodic Law.
Reason (R): Isotopes have similar chemical properties but different atomic masses.
(i) Both A and R are true and R is the correct explanation of A
(ii) Both A and R are true but R is not the correct explanation of A
(iii) A is true but R is false
(iv) A is false but R is true
Answer: (i) Both A and R are true and R is the correct explanation of A
Q.49. The element having electronic configuration 2, 8, 8 belongs to —
(i) Group 1
(ii) Group 17
(iii) Group 18
(iv) Group 2
Answer: (iii) Group 18
Q.50. Which of the following statements is correct regarding the Modern Periodic Law?
(i) Properties of elements are periodic functions of their atomic masses
(ii) Properties of elements are periodic functions of their atomic numbers
(iii) Properties of elements depend only on valency
(iv) Properties of elements are independent of atomic number
Answer: (ii) Properties of elements are periodic functions of their atomic numbers
SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions for HSLC Exam 2026–27
The SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions provided here are designed according to the latest SEBA (ASSEB) syllabus 2026–27. These SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions include conceptual MCQs, short answers, and long answer questions aligned with the HSLC exam pattern.
As per the updated HSLC structure, students must attempt 45 MCQs. Therefore, regular practice of SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions ensures strong preparation for MCQ-based and reasoning-type questions.
The SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions cover periodic trends, group and period characteristics, atomic radius, valency variation, and metallic character. Continuous revision using SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions improves conceptual clarity.
These Class 10 Periodic Classification of Elements Important Questions with MCQs are ideal for final revision. Consistent practice of SEBA Class 10 Science Chapter 5 Periodic Classification of Elements Important Extra Questions increases exam confidence and scoring ability.
Frequently Asked Questions (FAQ)
1. Why is Chapter 5 Periodic Classification of Elements important?
This chapter explains the modern periodic table, periodic trends, and properties of elements frequently asked in HSLC exams.
2. How many MCQs are asked in HSLC Science exam?
Students must answer 45 MCQs as per the latest HSLC Science exam pattern.
3. Are MCQs included in Chapter 5 important questions?
Yes, conceptual MCQs based on periodic trends and properties are included.
4. Are these questions based on SEBA syllabus?
Yes, all important extra questions are prepared strictly according to the latest SEBA (ASSEB) syllabus.
5. Do these include previous year questions?
Yes, previous year questions are included to match HSLC exam patterns.
6. Which topics are covered?
Topics include Mendeleev’s periodic table, modern periodic law, periodic trends, valency, atomic size, and metallic character.
7. Can practising these improve exam performance?
Yes, regular revision improves understanding of periodic trends and boosts MCQ accuracy.
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