Which of the following statements is not correct about the characteristics of cathode rays ?

1. They start from cathode and move towards anode.
2. They do not depend upon the material of the electrode.
3. Their characteristics depend upon the nature of the gas present in the cathode ray tube.
4. They travel in straight lines in the absence of an external electrical or magnetic fields.

Which statement is incorrect about electrons ?

1. Electron is a negatively charged particle.
2. Its mass is equal to the mass of neutron.
3. It is a constituent of cathode rays.
4. It is a basic constituent of all atoms.

An atom is neutral, its nucleus contains:

P — Negatively charged particles.

Q — Neutral particles.

R — Positively charged particles.

1. Only P
2. Only Q
3. Only R
4. Both Q and R

Postulates of modern atomic theory are:

P — Atoms of an elements may not be alike.

Q — Atoms of elements combine in small whole numbers to form molecules.

R — Atoms can neither be created nor destroyed.

1. Only P
2. Only Q
3. Only R
4. Both P and Q