When the atoms of gold sheet are bombarded with a beam of -particles, only a few alpha-particles get deflected where as most of them go straight undeflected. This is because:
| 1. | The force of attraction on the -particles by the oppositely charged electron is not sufficient. |
| 2. | The nucleus occupies much smaller volume as compared to the volume of atom. |
| 3. | The force of repulsion on fast moving -particles is very small. |
| 4. | The neutrons in the nucleus do not have any effect on -particles. |
Which of the following statements about an electron is/are correct?
| (a) | It has a negative charge and is lighter than a proton. |
| (b) | It has a negative charge and is heavier than a proton. |
| (c) | Its position is less fixed than that of a proton. |
| (d) | Its position is more fixed than that of a proton. |
| 1. | (a) only | 2. | (a) and (c) |
| 3. | (b) and (d) | 4. | (c) only |
Identify the pairs which are not isotopes?
(a) \(_{6}^{12}X, \ _{6}^{13}Y\)
(b) \(_{17}^{35}X, \ _{17}^{37}Y\)
(c) \(_{6}^{14}X, \ _{7}^{14}Y\)
(d) \(_{4}^{8}X, \ _{5}^{8}Y\)
1. (a), (d)
2. (b), (c)
3. (c), (d)
4. (b), (d)
Which of the following statements about the electron is incorrect?
| 1. | It is a negatively charged particle. |
| 2. | The mass of electron is equal to the mass of neutron. |
| 3. | It is a basic constituent of all atoms. |
| 4. | It is a constituent of cathode rays. |
Determine the identity of a species if it has 16 protons, 18 electrons, and 16 neutrons:
| 1. | \(S^{-}\) | 2. | \(Si^{2+}\) |
| 3. | \(P^{3-}\) | 4. | \(\mathrm{S}^{2-}\) |
In \(_{35}^{80}Br\), the number of protons, neutrons, and electrons are:
1. 25, 45, 45
2. 35, 45, 35
3. 45, 45, 35
4. 80, 35, 35