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The Fundamental Unit Of Life
Question
Helium atom has an atomic mass of 4 u and has two protons in its nucleus. How many neutrons it have?
Solution
The mass of an atom is given by the sum of the masses of protons and neutrons present in the nucleus.
Mass of atom =Protons +Neutrons
Since helium atom has a atomic mass of 4 u and it has two protons. Two protons contribute 2 u to atomic mass.
4u =2u +Neutrons
Neutrons =4-2 =2
Hence, it must contain 2 neutrons.
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Some More Questions From The Fundamental Unit of Life Chapter
Na+ has completely filled K and L-shells. Explain.
If Z = 3, what would be the valency of the element? Also, name the element.
Composition of the nuclei of two atomic species X and Y are given as under
X Y
Protons = 6 6
Neutrons= 6 6
Give the mass numbers of X and Y. What is the relation between the two species?
For the following statements, write T for True and F for False.
(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.
(c) The mass of an electron is about 1/2000 times that of proton.
(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.
Rutherford’s α-particle scattering experiment was responsible for the discovery of
Isotope of an element has
Number of valence electrons in Cl- ion are
Which one of the following is a correct ? Electronic configuration of sodium
(a) 2, 8,2 (b) 8, 2, 1 (c) 2, 1, 8 (d) 2, 8, 1.
Complete the following Table:
|
Atomic number |
Mass number |
Number of neutrons |
Number of protons |
Number of electrons |
Name of the atomic species |
|
9 |
- |
10 |
- |
- |
- |
|
16 |
32 |
- |
- |
- |
Sulphur |
|
- |
24 |
- |
12 |
- |
- |
|
- |
2 |
- |
1 |
- |
- |
|
- |
1 |
- |
1 |
0 |
- |
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