NEET UG » NEET MCQs » Electron MCQ

Electron MCQ

MCQ’s on Electron : Find the multiple choice questions on Electron MCQ , frequently asked for all competitive examinations.

What are electrons and how do they work?

Subatomic particles with an elementary charge of -1 are known as electrons. The charge held by an electron is the same as the charge held by a proton (but has an opposite sign).

As a result, electrically neutral atoms/molecules must have the same number of protons and electrons. Although the magnitude of the charges borne by protons and electrons are the same, an electron’s size and mass are substantially smaller than a proton’s (an electron’s mass is around 1/1836 that of a proton).

Electrons’ ChargeA negatively charged particle is an electron. The magnitude of the negative charge is

1.602 10-19 coulomb. An electron has a mass of 1/1837 that of a proton.

Electrons’ Mass

An electron has a mass of 9.10938356 10-31 kilograms. When compared to the mass of the proton, the electron has a tiny mass.

Because of their small size and mass, electrons’ properties can be explored more thoroughly using quantum mechanics rather than classical mechanics. Because matter acts differently at the quantum scale, this is the case. According to Heisenberg’s uncertainty principle, the uncertainty associated with the position and velocity of an electron is substantially greater than that associated with a proton or neutron. Atomic orbitals, which may be simply seen as zones surrounding the nucleus where the likelihood of finding a certain electron is highest, area where electrons are distributed around the nuclei of atoms

  1. Which of the following statements about cathode ray discharge tubes is incorrect?
    1. In cathode rays, the presence of a negative charge
    2. These rays are deflected by the magnetic field.
    3. It necessitates a high voltage supply
    4. In cathode rays, protons are present.

Answer-:D) In cathode rays, protons are present.

Clarification: In a cathode ray discharge tube, electric discharge occurs in partially evacuated tubes. Electrons make up the cathode rays. Cathode rays have a negative charge, and they are deflected by a magnetic field. A high voltage is required for a cathode ray discharge tube.

  1. Choose a value for the charge to mass ratio of electrons from the options.
    1. 1.758820 1011 C kg
    2. 1.758820 1011C kg
    3. 1.758823 1011 C kg
    4. 1.708820 1011 C kg

Answer-:A) 1.758820 1011 C kg

Clarification : J. J. Thomson, a British physicist, conducted tests and detected electron deflections in an electric or magnetic field. Finally, he estimated the charge-to-mass ratio of electrons as e/me = 1.758820 1011C kg-1. Charge and mass are measured in coulombs and kilogrammes, respectively.

  1. For a cathode ray discharge tube, which of the following conditions is appropriate?
    1. High voltage, low pressure
    2. Low voltage and low pressure
    3. Low voltage, high pressure
    4. High voltage and high pressure

Answer-: A) High voltage, low pressure

Clarification: Low and high pressures are appropriate settings for cathode ray discharge tubes. Evacuated tubes can be used to change the pressure. Current begins to flow through the tube after a high voltage is placed across the electrodes.

  1. Who carried out the oil drop test?
    1. R. A. Millikan
    2. J. J. Thomson
    3. Rutherford
    4. Galileo Galilei

Answer-: A) R. A. Millikan

Clarification: To determine the mass of oil droplets, R. A. Millikan conducted an oil drop experiment. He determined that charge only exists in integral multiples of e, i.e. q = ne; n = 1, 2, 3, etc., after observing how charge is transported in the experiment.

  1. Through his experiments, Thomson discovered that every substance in the universe is made up of .
    1. Neutrons
    2. Protons
    3. Electrons
    4. Mass

Answer-:C) Electrons

Clarification: Based on his tests with cathode ray discharge tubes, he determined that every substance in the cosmos is made up of electrons. He studied the movement of cathode rays as well as their charge-to-mass ratio.

  1. What happened when cathode rays hit zinc sulfide coating?
    1. a bright spot,
    2. blue light,
    3. ultraviolet rays, and
    4. white light

Answer-:A) a bright spot.

Clarification: The anode has been covered with zinc sulfide, a phosphorescent substance. When cathode rays collide with the anode, electrons collide with the Zinc sulfide screen, resulting in a brilliant spot.

  1. __________ are the lightest and tiniest particles produced by hydrogen (that is a positive ion).
    1. Electron
    2. Proton c)
    3. Neutron
    4. Particle

Answer-:b) Proton

Clarification: Rutherford discovered protons in 1911 through tests and also determined that positive charge is concentrated at the center of the atom and that it contains the majority of the atomic mass. In the year 1920, the name proton was given for the first time.

  1. What is the mass of a neutron in terms of the mass of electrons?
    1. 1838 times the mass of an electron
    2. 1/1838 times the mass of an electron
    3. 1832 times the mass of an electron
    4. 1/1832 times the mass of an electron

Answer-: a) 1838 times the mass of an electron

Clarification -:An electron has a mass of 0.00054 u. A proton has a mass of 1.00727 u. A neutron has a mass of 1.00867 u. Then 1.00867/0.00054 = 1838 is the mass of a neutron divided by the mass of an electron. As a result, the mass of a neutron is 1838 times that of an electron.

  1. Protons are neutrally charged particles.
    1. True
    2. False

Answer-:B) False

Clarification: Neutrons are neutrally charged particles, whereas protons are positively charged particles. Chadwick found neutrons when Beryllium is attacked by alpha particles. They have a little higher mass than protons.

  1. The model of organizations of  electron in atom is given by –
    1. R. A. Millikan
    2. J. J. Thomson
    3. Rutherford
    4. Galileo Galilei

Answer-:B) J. J. Thomson

Clarification: Thomson proposed an atom model in which electrons are implanted to form a stable electrostatic arrangement in which positive charge is spread evenly around a sphere. The assumption is that mass is distributed evenly. As a result, it goes by several names such as plum pudding, watermelon pudding, and raisin pudding model.