Which of the following statement is not correct about the characteristics of cathode rays?
| 1. | They start from the cathode and move towards the anode | 
| 2. | They travel in straight line in the absence of an external electrical or magnetic field | 
| 3. | Characteristics of cathode rays do not depend upon the material of electrodes in cathode ray tube | 
| 4. | Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube | 
| 1. | 2.4 ×10–19 g | 2. | 2.4 ×10–27 g | 
| 3. | 2.4 ×10–24 g | 4. | None of these | 
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. | 
Correct statement about the properties of the atom explained by the Thomson
model of an atom is:
| 1. | Overall neutrality of atom | 
| 2. | Spectra of a hydrogen atom | 
| 3. | Position of electrons, protons, and neutrons in an atom | 
| 4. | Stability of atom | 
Which of the following conclusions could not be derived from Rutherford's -particle scattering experiment?
| 1. | Most of the space in the atom is empty. | 
| 2. | The radius of the atom is about 10-10 m while that of a nucleus is 10–15 m. | 
| 3. | Electrons move in circular path of fixed energy called orbits. | 
| 4. | Electrons and the nucleus are held together by electrostatic forces of attraction. | 
Chlorine exists in two isotopic forms, Cl-37 and Cl-35, but its atomic mass is 35.5. This indicates the ratio of Cl-37 and Cl-35 is approximately:
1. 1:2
2. 1:1
3. 1:3
4. 3:1
Identify the pairs which are not of isotopes?
(a)
(b)
(c)
(d)
| 1. | (a), (d) | 2. | (b), (c) | 
| 3. | (c), (d) | 4. | (b), (d) | 
What property identifies two atoms as isobars?
| 1. | They have the same atomic number but different mass numbers. | 
| 2. | They have the same number of electrons but a different number of neutrons. | 
| 3. | They have the same number of neutrons but different numbers of electrons. | 
| 4. | The sum of the number of protons and neutrons is the same but the number of protons is different. | 
| Assertion (A): | All isotopes of a given element show the same type of chemical behaviour. | 
| Reason (R): | The chemical properties of an atom are controlled by the number of electrons in the atom. | 
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). | 
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). | 
| 3. | (A) is True but (R) is False. | 
| 4. | (A) is False but (R) is True. | 
| 1. | \(\mathrm {^{56}Fe }\) | 2. | \({ }^{57} \mathrm{Fe}\) | 
| 3. | \({ }^{57} \mathrm{Co}\) | 4. | \({ }^{60} \mathrm{Co}\) |