71. Which of the following states that "the properties of elements are the periodic function of their atomic numbers".
72. In the modern periodic table, in which period elements with atomic numbers 19 to 36 are placed?
73. The atomic number of actinium is-
74. Which of the following statements are correct?
1. There are 18 elements in the fourth and fifth period.
2. The seventh period is incomplete with 33 elements.
3. The sixth period has 32 elements.
1. There are 18 elements in the fourth and fifth period.
2. The seventh period is incomplete with 33 elements.
3. The sixth period has 32 elements.
75. Who was the first scientist to make periodic table of elements?
76. Elements in any common group are similar.
77. Match List I with List II
List-I
List-II
a. Element with smallest atomic radius
1. Cs
b. Element with largest atomic radius
2. F
c. Element with highest electron affinity
3. Br
d. Element with negative electron affinity
4. Cl
| List-I | List-II |
| a. Element with smallest atomic radius | 1. Cs |
| b. Element with largest atomic radius | 2. F |
| c. Element with highest electron affinity | 3. Br |
| d. Element with negative electron affinity | 4. Cl |
78. Which of the following statements is/are false regarding modern periodic table?
1. Elements in the modern periodic table are arranged in decreasing order of their atomic numbers.
2. Elements in the modern periodic table are arranged in increasing order of their atomic masses.
3. In the modern periodic table, isotopes are placed in adjacent groups.
4. Elements in modern periodic table are arranged in increasing order of their atomic numbers.
1. Elements in the modern periodic table are arranged in decreasing order of their atomic numbers.
2. Elements in the modern periodic table are arranged in increasing order of their atomic masses.
3. In the modern periodic table, isotopes are placed in adjacent groups.
4. Elements in modern periodic table are arranged in increasing order of their atomic numbers.
79. The correct increasing order of acidity of the oxide of Mn is -
80. Which element has atomic number 3?
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