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प्रश्न
(a) Which of the nuclear particles is present in the same fixed number in the atoms of any particular element?
(b) What do we call this number which is characteristic of a particular element?
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उत्तर
(a) The number of protons present in the atom of any particular element i.e., the atomic number is fixed.
(b) This number which is the characteristic of a particular element is called its atomic number.
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संबंधित प्रश्न
In Milikan’s experiment, static electric charge on the oil drops has been obtained by shining X-rays. If the static electric charge on the oil drop is - 1.282 × 10-18C, calculate the number of electrons present on it.
The atomic number of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is :
Draw the atomic diagram of the following element showing the distribution of – protons, neutrons and the electrons in the various shell of the atom.
Calcium – \[\ce{^40_20Ca}\]
[The upper number represent the – mass number and the lower number represent the – atomic number e.g. calcium – mass number = 40, atomic number = 20]
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
If an isotope of ‘H’ has mass no. = 2, how many electrons does it have.
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
If an isotope of ‘H’ has mass no. = 3, how many neutrons does it have.
Elements A, B and C have atomic numbers 9, 20 and 10 respectively.
- State which one is
(1) a non-metal,
(2) a metal,
(3) chemically inert.[A,B,C] - Write down the formula of the compound formed by two of the above elements.[BA2]
Complete the following table.
| Atomic Number | Mass Number | Number of Neutrons | Number of Protons | Number of Electrons | Name of the Element |
| 9 | ______ | 10 | ______ | ______ | ______ |
| 16 | ______ | 16 | ______ | ______ | ______ |
| ______ | 24 | ______ | ______ | 12 | Magnesium |
| ______ | 2 | ______ | 1 | ______ | ______ |
| ______ | 1 | 0 | 1 | 1 | ______ |
‘A’ is denoted by ______.
Electrons revolve around the nucleus in definite open shells.
Match the following:
| Column A | Column B | ||
| 1. | K shell | a. | 8 |
| 2. | L shell | b. | 32 |
| 3. | M shell | c. | 2 |
| 4. | N shell | d. | 18 |
