'Plum Pudding Model' for an atom was proposed by
- A.Antoine Lavoisier
- B.Robert Boyle
- C.Ernest Rutherford
- D.J. J. Thomson
Correct answer
Explanation
The correct answer is D, J. J. Thomson. Thomson proposed in 1904 that an atom is a sphere of positive charge with electrons embedded in it, like plums in a pudding or seeds in a watermelon.
Thomson had discovered the electron in 1897 through his work on cathode rays. Since atoms are neutral, he reasoned that the negative electrons must sit inside some spread-out positive charge, and that the atom's mass is spread evenly. The model explained why atoms are neutral but could not explain later experiments. In 1911, Rutherford's gold foil experiment showed that most alpha particles passed straight through while a few bounced back, proving that the positive charge is packed into a tiny nucleus.
A is wrong because Lavoisier is known for the law of conservation of mass and for naming oxygen and hydrogen. B is wrong because Boyle gave the law relating the pressure and volume of a gas. C is wrong because Rutherford replaced the plum pudding model with the nuclear model.
Exam tip: Thomson, plum pudding (1904); Rutherford, nucleus (1911); Bohr, fixed orbits (1913).
Practice Questions
View allThe mass number of an element is NOT changed when it emits
- A.Alpha and Beta radiations only
- B.Alpha and Gamma radiations only
- C.Beta and Gamma radiations only
- D.Alpha, Beta and Gamma radiations
Show answer
Neither beta nor gamma emission changes the total number of protons and neutrons in a nucleus, so the mass number stays the same.
Read the full explanation →Which one among the following statements about facilitated transport in plants is correct?
- A.All passive transports are types of facilitated transport.
- B.Facilitated transport is an example of active transport.
- C.Water moves across plasma membrane by active transport.
- D.Facilitated transport requires assistance of carrier proteins.
Show answer
In facilitated transport, molecules cross the membrane with the help of membrane proteins, while still moving down their concentration gradient.
Read the full explanation →Who among the following has coined the term 'Quark', the fundamental particles that make up protons and neutrons in an atomic nucleus ?
- A.Richard Feynman
- B.Murray Gell-Mann
- C.Albert Einstein
- D.Niels Bohr
Show answer
The American physicist Murray Gell-Mann proposed quarks in 1964 and gave them their name. Gell-Mann, and independently George Zweig, suggested that protons, neutrons and other such particles are built from smaller units.
Read the full explanation →The spindle fibre is attached to which of the following specific regions of the chromosomes?
- A.Kinetochore
- B.Chromonema
- C.Telomere
- D.Centriole
Show answer
Spindle fibres attach to the kinetochore, a disc-shaped protein structure on the centromere of each chromosome. During cell division the spindle, made of microtubules, pulls the copies of each chromosome apart.
Read the full explanation →Which one of the following is the chemical name of heavy water?
- A.Hydrogen oxide
- B.Deuterium dioxide
- C.Deuterium oxide
- D.Heavy hydrogen oxide
Show answer
Heavy water is D₂O: two atoms of deuterium joined to one atom of oxygen. Deuterium is the isotope of hydrogen with one proton and one neutron in its nucleus, so it is about twice as heavy as ordinary hydrogen.
Read the full explanation →