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प्रश्न
Calculate the valency of element X whose atomic number is 9.
उत्तर
The electronic configuration of element X with atomic number 9 is 2,7
Its valency = 8−7 =1 Hence, the valency of element with atomic number 9 is 1.
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संबंधित प्रश्न
Elements in the same group show the same valency. Give scientific reason.
Which element has twice as many electrons in its second shell as in its first shell?
Differentiate between Normal elements and Transition elements.
The atomic number of an element is 20. In modern periodic table, this element is placed:
(a) 2nd period
(b) 4th period
(c) 3rd period
(d) 1st period
Taking into consideration the period of the elements given below, answer the following questions:
| Elements | Atomic Radius (pm) |
| O | 66 |
| B | 88 |
| C | 77 |
| N | 74 |
| Be | 111 |
| Li | 152 |
- Arrange the above elements in decreasing order of their atomic radii.
- State the period to which the above elements belong.
- Why this arrangement of elements is similar to the above period of modern periodic table?
- Which of the above elements have the biggest and the smallest atom?
- What is the periodic trend observed in the variation of atomic radius while going from left to right within a period?
'In a group, the atomic radii increase with increasing period number', explain this statement and justify it with reference to group 17.
Select the correct answer
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Atomic numbers of elements A, B, C, D, E, F are 8, 7, 11, 12, 13 and 9 respectively. State the type of ions they form.
An element A has 2 electrons in its fourth shell. State:
is it an oxidising or reducing agent
Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.
