Advertisements
Advertisements
प्रश्न
The mass number of an element is 18. It contains 7 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?
उत्तर
(b) When mass number is 18 and number of electrons is 7, then:
(i) No. of protons = No. of electrons = 7
(ii) No. of neutrons = Mass no. – No. of protons = 18 – 7 = 11
(iii)Atomic no. = 7
APPEARS IN
संबंधित प्रश्न
FILL IN THE BLANK
Rutherford won the Nobel Prize in 1908 for his investigations in the field of ......................
TRUE \ FALSE
After the emission of a beta-particle, the atomic number of the atom increases by one.
Fill in the blanks- The number of protons in the nucleus of an atom is called its ....................
From the symbol `""_12^24"Mg"`
, state the mass number, the atomic number and electronic configuration of magnesium.
If an atom ‘A’ has atomic number 19 and mass number 39, state –
- Its electronic configuration.
- The number of valence electrons it possesses.
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.
The ratio of the radii of hydrogen atom and its nucleus is ~ 105. Assuming the atom and the nucleus to be spherical,
- what will be the ratio of their sizes?
- If atom is represented by planet earth ‘Re ’ = 6.4 ×106 m, estimate the size of the nucleus.
The Atomic number of an element is 20. It has ______ valence electrons.
K and L shells can accommodate a maximum of 2 and 8 electrons respectively.
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 |
