Objective

Question-2. Which elements do not take part in chemical reactions?

Ans- inactive

Question-3. The method of grouping elements with similar properties into a group is called—

Ans- recurring classification of elements

Question-4. How many elements were discovered by 1800 AD?

Ans- of 30 elements

Question-5. On what basis were the elements initially classified?

Ans- on the basis of atomic mass

Question-6. How many elements did Dobereiner put and decorate in his law of triples?

Ans- Put three elements with similar properties and arrange them in ascending order (in increasing order).

Question-7. On what basis did Dabereiner designate three elements with similar properties?

Ans- on the basis of atomic mass

Question-8. 1Pm Pico Meter Equals?

Ans- 10⁻¹²m

Question-9. When and where was Dobereiner born?

Ans- 1817 AD (in Germany)

Question-10. What is Newlands' principle called?

Ans- octet theory

Question-11. On what basis did Newlands decorate the elements?

Ans- In increasing order of atomic mass

Question-12. With which element did Newlands start and end with?

Ans- Starting with Hydrogen (H) and ending with Thorium (Tr)

Question-13. What is the repetition of elements with common properties after a certain interval called?

Ans- frequency

Question-14. To which element did Newlands's octet theory apply?

Ans- up to calcium (Ca)

Question-15. To which elements Newlands' octet theory was applicable and on which elements could not apply?

Ans- Applicable to lighter elements but not applicable to elements with higher atomic mass

Question-16. Which property of elements is considered fundamental by Newlands for the classification of elements?

Ans- atomic mass of elements

Question-17. When and where was Newlands born?

Ans- 1866 AD (in England)

Question-18. How many total elements were known during Mendeleev's time?

Ans- 63 elements

Question-19. Which elements did Mendeleev use as his basis for the classification of elements?

Ans- oxides and hydridos of oxygen and hydrogen

Question-20. In what order did Mendeleev arrange the elements?

Ans- In increasing (ascending) order of atomic mass

Question-21. According to Mendeleev's periodic law, the properties of elements are their atomic mass.

Ans- periodic function

Question-22. How many horizontal rows and vertical columns are there in Mendeleev's periodic table?

Ans-

Horizontal rows → 6

Vertical pillar → 8

Question-23. What are Mendeleev's horizontal rows and vertical columns called?

Ans-

Horizontal Rows → Periodic

Vertical column → group or square

Question-24. When was Mendeleev's periodic table first published?

Ans- 1872 AD (in German magazine)

Question-25. Elements with similar properties were placed in Mendeleev's periodic table?

Ans- in a group

Question-26. Which element could not be given by Mendeleev in his periodic table?

Ans- of hydrogen

Question-27. Is hydrogen a metal or a non-metal

Ans- Metal

Question-28. What are the properties of hydrogen?

Ans- halogen

Question-29. Where is hydrogen placed in Mendeleev's periodic table?

Ans- In I (A) and in VII (B)

Question-30. In which group are the three elements placed together in Mendeleev's periodic table?

Ans- in group VIII

Question-31. In Mendeleev's periodic table, which elements have similar chemical properties, yet they are placed in a separate group?

Ans- Cu (Copper) and Hg (Mercury)

Question-32. Which group of elements was not in Mendeleev's original periodic table?

Ans- Zero (Class 18)

Question-33. What was made for the classification of elements after Mendeleev's periodic table?

Ans- modern periodic law

Question-34. Who propounded the modern periodic law?

Ans- British scientist Henry Moseley

Question-35. When and where was Henry Moseley born?

Ans- 1913 AD (in England)

Question-36. What is the modern periodic law based on?

Ans- on the atomic number of the elements

Question-37. In the modern periodic law, the properties of elements are periodic functions of their ………….?

Ans- atomic number

Question-38. How were the elements arranged in the modern periodic law?

Ans- In increasing order of atomic number

Question-39. How many periods and groups are there in the modern periodic table?

Ans-

Periodic (horizontal rows) → 7

Group (class) → 18

Question-40. What is the period called in the modern periodic table?

Ans-

first period → very short period

Second and third period → short period

4th and 5th period → Long period

6th period → very long period

7th period → still incomplete

Question-41. Which element is on the left and right side of the modern periodic table?

Ans-

On the left side → element is metal.

Right side → Element is non-metal.

(Centre) Shaded → Element is a metalloid.

Question-42. Metals Into how many blocks are the periodic table divided?

Ans- 4

Question-43. What is the group block in the modern periodic table called?

Ans-

to group 1 and 2 → S block

Groups 3 to 12 → d block

Groups 13 to 18 →p block

The elements located below are called lanthanides and actinides. → f block

Question-44. Who is the first member of the first period in the modern periodic table?

Ans- Hydrogen (H)

Question-45. Which period is still incomplete?

Ans- last member of seventh period

Question-46. What is the first member and last member in the modern periodic table?

Ans-

first member → alkali metals

last member → inert (inert gas)

Question-47. What is the maximum number of electrons in a shell?

Ans- 2n² (where n = number of shells)

Question-48. What is written below the elements and to the right of the element in the modern periodic table?

Ans-

under the element → Atomic Number (Atomic Number)

to the right of the element → electronic configuration

Question-49. What happens to the atomic number as you move from left to right in the modern periodic table?

Ans- Growth

Question-50. What are the elements from group 3 to group 12 called?

Ans- transition element

Question-51. What are the elements of group 1, 2, 17 and 18 called?

Ans-

group 1 elements → alkali is metal

group 2 elements → alkaline earth is metal

Elements of Group 17 → halogen

Elements of Group 18 → inert gas is called

Question-52. Cobalt (Co) has atomic number 27 and Nickel (Ni) has atomic number 28. Which element is placed first in the modern periodic table?

Ans- Cobalt is placed first and Nickel second.

Question-53. Which has been given a definite place in the modern periodic table?

Ans- to hydrogen

Question-54. What is the order of the elements in the modern periodic table?

Ans- in order of atomic numbers

Question-55. In which of these periods is the space left for the unknown element?

Ans- in the seventh period

Question-56. In the modern periodic table, metals and non-metals are separated from

Ans- metaphorically

Question-57. How are the elements arranged in the modern periodic table?

Ans- From left to right in increasing order of atomic number

Question-58. Going from top to bottom in a group of the periodic table is the periodic number.

Ans- increases

Question-59. The number of electrons they give up or gain in order to complete an octet for an element is called

Ans- valency of elements

Question-60. What is the valency of a metallic element equal to?

Ans- equal to the number of its valence electrons

Question-61. The valency of all the elements in a group going from top to bottom is ………….

Ans- same

Question-62. On moving from left to right in a period, the size of the atoms of the elements is ………….

Ans- decreases

Question-63. What is the size of an atom represented by?

Ans- from its atomic radius

Question-64. On going from top to bottom in a group, the size of an atom is ……….

Ans- decreases

Question-65. Which atom has the largest size and which atom has the smallest size in a period?

Ans- Alkali metals have the largest atomic size and the halogen atom has the smallest size.

Question-66. What does halogen mean?

Ans- salt maker

Question-67. The metallic property of elements on moving from left to right in a periodic table is ……….

Ans-

Metallic Properties → Decreases

Nonmetallic Properties → Increases

Question-68. The metallic property of elements on going down from top to bottom in a group is ……….

Ans-

Metallic Properties → Increases

Nonmetallic Properties → Decreases

Question-69. In a group of metals, the electricity is positive from top to bottom.

Ans- increases

Question-70. In a group of non-metals, the electricity is negative ............ on going from top to bottom.

Ans- decreases

Question-71. What are oxides of metals and oxides of non-metals?

Ans-

metal oxides → alkaline

nonmetal oxides → acidic

Question-72. What is the tendency of electrons in oxides of metals and oxides of non-metals.

Ans-

tendency to lose electrons → decreases

tendency to accept electrons → increases

Question-73. The tendency of metals to accept electrons from top to bottom in the group is ……….

Ans- increases

Question-74. What is the maximum number of electrons that can remain in the third shell of an atom?

Ans- 18

Question-75. Which period has the most elements?

Ans- sixth

Question-76. Who is the element of the zero square?

Ans- He (Helium)

Question-77. What is the maximum number of electrons that can remain in the second shell of an atom?

Ans- 8

Question-78. How many elements are there in the first period?

Ans- 2

Question-79. How many elements are there in the first group?

Ans- 7

Question-80. What are the compounds formed by the transfer of electrons called?

Ans- legal connector

Question-81. The members of the first group of the periodic table are?

Ans- alkaline metals