Questions
J. J. Thomson was awarded the Nobel Prize for Physics for his work on the discovery of electrons. Which of the following was/were suggested by Thomson in his model of atom?
- An atom consists of a positively charged sphere and the electrons are embedded in it.
- An atom consists of a negatively charged sphere and the electrons are embedded in it.
- The negative and positive charges are equal in magnitude.
- Both (1) and (3)
- Both (2) and (3)
Who discovered neutrons?
- J. J Thomson
- John Dalton
- Ernest Rutherford
- Eugen Goldstein
- James Chadwick
Which of the following is incorrect about the nucleus?
- It is the central part of an atom.
- It is neutral in charge.
- All protons and neutrons are present in this region.
- It is 105 times smaller than the size of the atom.
- None of these
The atomic number of an element signifies the number of
- protons in the nucleus
- electrons in the nucleus
- electrons in the extranucleur part
- protons in the extranucleur part
- electrons and protons in the nucleur part
Which of the following elements does not contain any neutron?
- Helium
- Krypton
- Oxygen
- Hydrogen
- Sodium
Which of the following particles determine the mass of an element?
a. Neutron
b. Electron
c. Proton
- a, b and c
- a and b
- b and c
- a and c
- only a
Isotopes are
- atoms of the same element
- atoms of different elements
- molecules of the same element
- radicals of the same element
- atoms with the same atomic mass
Which of the following statements is incorrect for the 'model of atom' as proposed by Rutherford?
- There is a positively charged centre in an atom called the nucleus.
- Nearly all the mass of an atom resides in the nucleus.
- The electrons revolve around the nucleus in circular paths.
- Nucleus contains protons and neutrons.
- The size of the nucleus in the atom is very small.
Which of the following isotopes is/are paired incorrectly with its/their application?
a. Uranium - fuel in nuclear reactors
b. Cobalt - treatment of cancer
c. Iodine - determining age of old wooden objects
- a only
- b only
- c only
- a and b
- b and c
Which of the following postulates were put forward by Neils Bohr about the model of an atom?
a. Only certain special orbits known as discrete orbits of electrons, are allowed inside the atom.
b. While revolving in discrete orbits, the electrons do not radiate energy.
c. The orbits or shells are called energy levels.
- a, b and c
- a and b
- b and c
- only a
- only c
Which of the following is/are the isotopes of hydrogen atom?
a. Protium
b. Deuterium
c. Tritium
d. Actinium
- a and b
- b and c
- c and d
- a, b and c
- b, c and d
Which of the following is/are correct about canal rays?
a. They are positively charged radiations.
b. They are negatively charged radiations.
c. J. J. Thomson discovered the presence of canal rays in a gas discharge.
- a and c
- b and c
- only a
- only b
- only c
Which of the following statements is/are correct?
a. An atom is divisible and consists of charged particles.
b. E. Goldstein identified the electron.
c. The mass of an electron is considered to be negligible and its charge is minus one.
- a only
- b only
- c only
- a and c
- a, b and c
Which of the following statements is/are correct about the characteristics of an atom?
a. Atoms are electrically neutral.
b. Nucleus of an atom is positively charged.
c. The protons and neutrons in a nucleus rearrange themselves due to emission of y-rays.
- a only
- b only
- c only
- a and b
- a, b and c
Which of the following is not a characteristic of cathode rays?
- They travel in straight lines.
- They are deflected towards negative plate, thus showing electrons.
- They ionise the gas through which they pass.
- They can penetrate through thin metallic sheet.
- They can produce X-rays.