The Fundamental Unit of Life
What are the differences in the discharge tubes used to study cathode rays and the positive rays?
A cathode ray discharge tube is essentially a glass tube with closed ends. Two metal plates which serve as cathode and anode are sealed at the two ends of the glass tube.
The discharge tube used to study anode rays has the perforated plate serving as cathode and is sealed in the middle of the glass tube.
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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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