Class 10 Science MCQ Chapter 5 Periodic Classification of Element, Class 10 Science MCQ Question Answer, Class 10 Science Multiple Choice Question Answer to each chapter is provided in the list of SCERT Science Class 10 Objective Types Question Answer so that you can easily browse through different chapters and select needs one. Class 10 Science MCQ Chapter 5 Periodic Classification of Element Question Answer can be of great value to excel in the examination.
SCERT Class 10 Science MCQ Chapter 5 Periodic Classification of Element
SCERT Class 10 General Science MCQ Chapter 5 Periodic Classification of Element Notes covers all the exercise questions in SCERT Science Textbooks. The NCERT Class 10 Science MCQ Chapter 5 Periodic Classification of Element provided here ensures a smooth and easy understanding of all the concepts. Understand the concepts behind every chapter and score well in the board exams.
Periodic Classification of Element
Chapter – 5
Multiple Choice Questions & Answers
1. Find out the metalloid from the following elements-
(a) Sodium.
(b) Aluminium.
(c) Chlorine.
(d) Boron.
Ans: (d) Boron.
2. In a period of the periodic table of elements, on moving from left to right the atomic radius-
(a) Increases.
(b) decreases.
(c) Remains same.
(d) None of the above.
Ans: (b) decreases.
3. Which one of the following is a Dobereiner’s triads?
(a) Li, Na, Ca
(b) K, Sr, Ba
(c) Ca, Sr, Be
(d) Cl, Br, I
Ans: (d) Cl, Br, I
4. The atomic number of an elements is more fundamental property than its atomic mass-Who put forward this statement?
(a) Mendeleev.
(b) Dobereiner.
(c) Bohr.
(d) Henry Moseley.
Ans: (d) Henry Moseley.
5. Elements of second period are Li, Be, B, C, N, O, F and Ne-which one of these has the largest atom?
(a) Li
(b) Be
(c) Ne
(d) F
Ans: (a) Li
6. Among the elements from the first group Li, Na, K, Rb, Cs and Fr-which one has the larg- est atom?
(a) Rb
(b) Cs
(c) Li
(d) Fr
Ans: (d) Fr
7. In Modern Periodic Table. When we move from top to bottom in a group the atomic size of the elements-
(a) Increases.
(b) decreases.
(c) Remains same.
(d) None of the above.
Ans: (a) Increases.
8. When we move from top to bottom in a group in Modern Periodic Table, the valency of elements –
(a) decreases.
(b) Increases.
(c) Remains same.
(d) None of the above.
Ans: (c) Remains same.
9. When we move from left to right Across a period in Modern Periodic Table, the valency of elements-
(a) decreases.
(b) Increases.
(c) Remains same.
(d) First increases, then starts to decrease.
Ans: (d) First increases, then starts to decrease.
10. The tendency of elements to lose electrons (Metallic or electroposi- tive property) in a group of periodic table-
(a) Decreases.
(b) Increases.
(c) Remain same.
(d) None of the above.
Ans: (b) Increases.
11. The tendency of elements to lose electrons (Metallic property) in a period of periodic table-
(a) Decreases.
(b) Increases.
(c) Remain same.
(d) None of the above.
Ans: (a) Decreases.
12. When we move from left to right across a period in the periodic table, the tendency of elements to gain electrons (Non-metallic or electronegative property)-
(a) Decreases.
(b) Increases.
(c) Remain same.
(d) None of the above.
Ans: (b) Increases.
13. The tendency of elements to gain electrons (Non-metallic prope erty) in a group as we go from top to bottom in the periodic table-
(a) Decreases.
(b) Increases.
(c) Remain same.
(d) None of the above.
Ans: (a) Decreases.
14. The formula of the oxide of the element K using Mendeleev’s Periodic table is-
(a) KO₂
(b) K₂O
(c) K₂O₃
(d) KO
Ans: (b) K₂O
15. An elements X forms compound with formula X₂O by reacting with oxygen, Element X is likely to be in the same group of the periodic table
(a) Na
(b) Mg
(c) Al
(d) Si
Ans: (a) Na
Very Short & Short Type Questions and Answers:
1. What is the need for classification of elements?
Ans: We know about 118 elements at present. It is not easy to study each of this large number of elements individually. If we make some groups of elements on the basis of the similarities in their properties, it become easier to study the elements by simply studying this groups.
2. What are Dobereiner’s triads?
Ans: Dobereiner tried to arrange the elements with similar properties in some groups. He identified some groups containing three elements in each. These groups are known as Dobereiner’s triads.
3. Give one examples of Dobereiner’s triads.
Ans:
| Li | Ca | CI |
| Na | Sr | Br |
| K | Ba | I |
4. Give a specific property of a Dobereiner’s triad.
Ans: When the elements in a triad are arranged in the increasing order of their atomic masses, the atomic mass of the middle element become roughly equal to the average of the atomic masses of the other two elements.
5. What is Newlands law of octaves?
Ans: When English scientist John Newlands arranged 56 elements known at his time in the increasing order of their atomic mass, he found that the properties of every eighth element were similar to those of the first. He compared this to the octaves found in music and hence it is called Newlands’ law of octaves.
6. On what basis Mendeleev arranged the elements in his periodic table?
Ans: Mendeleev arranged the elements in his periodic table on the ba is of one of their fundamental properties, i.e. atomic mass and also on the basis of the similarities in their chemical properties.
7. On which thing Mendeleev concentrated for the chemical properties of the elements?
Ans: On the formulae of the compounds made by the elements with oxygen and hydrogen.
8. Among the chemical properties why did Mendeleev concentrate on the compounds formed by the elements with oxygen and hydrogen?
Ans: Because oxygen and hydrogen were very reactive elements and they formed compounds with most of the elements.
9. To classify an element, what was considered by Mendeleev as one of the basic property of the element?
Ans: The formulae of the oxide and the hydride formed by the element.
10. State Mendeleev’s periodic low.
Ans: Properties of elements are the periodic function of their atomic masses.
11. Mendeleev left some gaps in his periodic table. Do you think them as an anomaly? Give reason.
Ans: I do not think so. Because Mendeleev could successfully predict the existence of some elements in those gaps which had not been discovered fill that time.
12. How were the elements named by Mendeleev as Eka-Boron, Eka-alu-minium and Eka-silicon renamed after their discovery?
Ans: As scandium, Gallium and Germanium respectively.
13. Who for the first time showed that the atomic number of an element is a more fundamental property than its atomic mass?
Ans: Henry Mosely.
14. State the Modern periodic law.
Ans: Properties of elements are the periodic function of their numbers.
15. How many elements are there in the first, second, third and the fourth period of modern periodic table?
Ans: 2,8, 8, and 18 respectively.
16. Determine the valency of the following elements
(i) Magnesium (12).
(ii) Sulphur (16).
Ans: (i) Valency of Magnesium (2,8,2) is
2. Valency of sulphur (2,8,6) is 2.
17. How does valency of elements change when we move from left to right in a period?
Ans: First the valency increases from 1 to 4 and then starts decreasing from 4 to 0.](For the first three periods)
18. How does valency change when we move from top to bottom in a group?
Ans: Valency of elements in a group remains same.
19. What is atomic radius or atomic size?
Ans: The distance between the centre of the nucleus and the outermost shell of on atom of an element is called its atomic radius. Atomic radius of an element gives its atomic size.
20. How does atomic radius change an moving from left to right in a period?
Ans: Decreases gradually.
21. How does atomic size change on moving from top to bottom in a group?
Ans: Increases gradually.
22. Where do you find the metals and nonmetals in the modern periodic table?
Ans: Metals are found towards the left of the Modern Periodic Table while the nonmetals are found towards the right.
23. How does the metallic property (tendency to lose electrons) change in a period of Modern Periodic Table?
Ans: Decreases gradually.
24. How dose the metallic property change in a group in modern periodic table?
Ans: Increases gradually.
25. How does the non-metallic property (tendency to gain electrons) change in a period of Modern periodic Table?
Ans: Increases gradually.
26. How does non-metallic property change in a group of Modern Periodic Table?
Ans: Decreases Gradually.
27. Write electronic configuration of the following elements and find out their period number and the group number in Modern Periodic Table.
(a) Calcium.
(b) Fluorine.
(c) Lithium.
Ans: Calcium – 2, 8, 8, 2
Period number = 4 [As number of shells is 4]
Group number = 2 [As number of valence electron=2]
[ Fluorine- 2, 7
Period number = 2 [As number of shells is 2]
Group number =17 [Number of valance electrons, 7+10=17]
[Lithium-2,1
Period number = 2 [ As number of shells =2]
Group number = 1 [ As number of valence electron=1]
28. Write one achievement of Mendeleev’s periodic table.
Ans: Noble gases were discovered much later after Mendeleev had formulated his periodic table. When they were discovered, they could be placed in a new group in Mendeleev’s periodic table without disturbing the existing order.
29. Write one limitation of Mendeleev’s classification.
Ans: Hydrogen could not be given a fixed position in Mendeleev’s table.
30. What was the reason for the late discovery of the noble gases?
Ans: Noble gases are inert and they are present in the atmosphere in a very low quantity.
31. What are isotopes?
Ans: The atoms of the same element which have same atomic numbers but different mass numbers are called the isotopes of the element.
32. Give examples of isotopes.
Ans: Three isotopes of hydrogen are- Protium (¹₁H), Deuterium (₁²H) and Tritium (³₁H).
33. How did isotopes pose a challenge to Mendeleev’s periodic table?
Ans: Mendeleev prepared his periodic table in the increasing order of the atomic masses of the elements. The isotopes of the same element have different atomic masses, though they have similar chemical properties.
34. Why was it not possible to predict how many new elements would be discovered between two elements in Mendeleev’s periodic table?
Ans: Because on moving from one elements to the next in Mendeleev’s periodic table, the atomic mass of the elements dose not increase in a regular manner.
35. What are metalloids or semimetals?
Ans: The elements which show same properties of both metals and nonmetals are called metalloids.
36. Give examples of two metalloids.
Ans: Boron, Silicon.
37. To which of the following elements, an element with electronic configuration 2,8,1 will have similar chemical properties?] (Atomic numbers are given in the parentheses.)
K (19), Cl (17), Mg(12), Ar(18)
Ans: K(19).
38. Which type of chemical bond will be formed between two elements with atomic numbers 12 and 17?
Ans: Electrovalent bond.
39. Write the chemical formula for the compound formed between two elements with atomic numbers 12 and 17.
Ans: AB₂
40. Did Dobereiner’s triads also exist in the columns of Newlands’s Octaves?
Ans: Yes. It is (Li, Na, K).
41. What was the limitation of Dobereiner’s classification?
Ans: The limitation of Dobereiner’s classification was that only three triads were identified out of the elements known at the time of Dobereiner.
42. What was a limitation of Newland’s Law of Octaves?
Ans: Only elements up to calcium could be fitted into his Scheme of Octave.
43. Use Mendeleev’s Periodic Table to predict the formulae for the oxides of K, C, Al, Si, Ba.
Ans: K₂O, CO₂, Al₂O₃, SiO₂, BaO
44. Besides gallium, which other elements have since been discovered that were left by Mendeleev in his periodic Table? (any two)]
Ans: Scandium, Germanium.
45. Why do you think the noble gases are placed in a separate group?
Ans: Because, noble gases have stable electronic configurations as their outer most shells are completely filled with electrons.
46. Name two elements you would expect to show chemical reaction similar to magnesium.
Ans: Beryllium, Calcium.
47. Write the name of
(a) Three elements having one electron in the outermost shell.
Ans: Lithium, Sodium and Potassium.
(b) Two elements having two electrons in the outermost shell.
Ans: Beryllium and Magnesium.
(c) Three elements having fully filled outermost shell.
Ans: Helium, Neon and Argon]
48. Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements?
Ans: There is only one electron in the outermost shell in each of these elements.
49. Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?
Ans: The outermost shell of atoms of these elements are fully filled with electrons.
50. By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic.
Ga, Ge, As, Se, Be
Ans: Be
51. Which element has
(a) Two shells, both of which are completely filled with electrons?
Ans: Of neon (28)
(b) 2.8.2 The electronic configuration 2, 8, 2?
Ans: Of magnesium
(c) A total of three shells, with four electrons in its valence shell?
Ans: Of silicon 2, 8, 4
(d) a total of two shells, with three electrons in its valence shell?
Ans: Of boron (2, 3)
(e) Twice as many electrons in its second shell as in its first shell?
Ans: Of carbon (2, 4)
52. What property do all elements in the same column of the Periodic Table as boron have in common?
Ans: Each of these elements has three electrons in the valence shell of their atoms and they have valency three.
53. What property do all elements in the same column of the Periodic table as fluorine have in common?
Ans: Each of these elements has seven electrons in the valence shell of their atoms and they have valency one.
54. An atom has electronic configuration 2, 8, 7. What is the atomic number of this element?
Ans: 17.
