Thompson was the first to discover a subatomic particle - the electron. What are the others?
neutrons & positrons
protons & neutrons
positrons & quarks
protons & positrons
A positively charged particle found in the nucleus is called a
Only protons & neutrons can be distinguished by mass, charge and position in an atom.
99.9% of the atom's mass is found where?
The nucleus is ____________ charged.
Who discovered the electron?
Why was the Thomson’s Model of an atom failed?
i. It could not explain the screening of negative charges from that of positive
ii. It did not tell about the presence of electrons
iii. It did not give an idea about the discrete energy levels
iv. It explained the atom as a whole to be electrically neutral
Choose the correct option from the following:
Both (i) & (iii)
Both (ii) & (iv)
Which of the following statements is incorrect about the structure of an atom?
i. The whole mass of an atom is concentrated in the nucleus
ii. The atom is an indivisible particle
iii. The atom as a whole is neutral
iv. All the atoms are stable in their basic state
Choose the right option among the following:
(i) and (iii)
(ii) and (iv)
none of these
Which of the following correctly represent the electronic distribution in the Mg atom?
3, 8, 1
2, 8, 2
1, 8, 3
8, 2, 2