Which one of the following statements about the properties of neutrons is not correct?
- A.Neutron mass is almost equal to proton mass.
- B.Neutrons possess zero charge.
- C.Neutrons are located inside the atomic nuclei.
- D.Neutrons revolve around the atomic nuclei.
Correct answer
Explanation
The correct answer is D, Neutrons revolve around the atomic nuclei. Neutrons sit inside the nucleus with protons; it is the electrons that move around the nucleus.
The neutron was discovered by James Chadwick in 1932, and he received the Nobel Prize in Physics for it in 1935. It is an electrically neutral particle with a mass of about 1.675 × 10⁻²⁷ kg, very slightly more than that of the proton. Protons and neutrons together are called nucleons and are held in the nucleus by the strong nuclear force. The number of neutrons decides an element's isotopes: carbon-12 and carbon-14 both have six protons but six and eight neutrons respectively. Ordinary hydrogen, protium, is the only common atom with no neutron.
A is wrong because a neutron's mass is indeed almost the same as a proton's. B is wrong because neutrons really carry no charge. C is wrong because neutrons really are found inside the nucleus.
Exam tip: Electron: Thomson (1897); proton: Rutherford; neutron: Chadwick (1932); protium has no neutron.
Practice Questions
View allThe instrument used for detecting the presence of electric current in a circuit is
- A.Refractometer
- B.Galvanometer
- C.Viscometer
- D.Diffractometer
Show answer
A galvanometer detects whether a small electric current is flowing in a circuit and shows its direction. A moving-coil galvanometer has a coil placed between the poles of a magnet.
Read the full explanation →Reverberation is a phenomenon associated with a
- A.multiple refraction of sound.
- B.multiple reflection of sound.
- C.single refraction of sound.
- D.single reflection of sound.
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Reverberation is the persistence of sound in a hall after the source has stopped, caused by repeated reflections from the walls, ceiling and floor.
Read the full explanation →Which one of the following is NOT a basic property of electric charge ?
- A.Charges can be added
- B.Charge is conserved
- C.Charge on a body is always an integral multiple of an electron or a proton charge
- D.Charges can be created and destroyed in an isolated system
Show answer
This goes against the conservation of charge: the total charge of an isolated system always stays the same. Electric charge has three basic properties.
Read the full explanation →Which of the following organelles have their own DNA and ribosomes?
- A.Endoplasmic reticulum and Golgi bodies
- B.Mitochondria and Chloroplast
- C.Endoplasmic reticulum and cytoskeleton
- D.Cell wall and nucleolus
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These two organelles carry their own circular DNA and their own small (70S) ribosomes, so they can make some of their own proteins.
Read the full explanation →Which one of the following statements is NOT correct ?
- A.All proteins are enzymes
- B.Mostly enzymes are proteins
- C.All fats are energy rich compounds
- D.Glucose is a common carbohydrate
Show answer
This statement is false: enzymes are mostly proteins, but most proteins are not enzymes. Proteins do many jobs in the body.
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