Discovery of Subatomic Particles (Electron, Proton, Neutron) MCQs
Practice Discovery of Subatomic Particles (Electron, Proton, Neutron) multiple-choice questions from Structure of the Atom (Class 9 Science) - tap an answer for instant feedback and a step-by-step solution. Practice the full set free on the RankByte app.
Discovery of Subatomic Particles (Electron, Proton, Neutron)Quiz - Solve & Score
Q1. An atom turned into an ion by losing 12 electrons holds what charge in coulombs?
- A.7.5*10^-19 C
- B.1.6*10^-19 C
- C.19.2*10^-19 C
- D.19.2*10^-18 C
Answer: C. 19.2*10^-19 C
Each electron is 1.6*10^-19 C. Removing 12 electrons gives a net charge of 12 * 1.6*10^-19 = 19.2*10^-19 C.
Q2. A pollen speck floating in air traps 50 electrons; what is the magnitude of its charge?
- A.80*10^-18 C
- B.31.25*10^-19 C
- C.80*10^-19 C
- D.1.6*10^-19 C
Answer: C. 80*10^-19 C
Each electron carries 1.6*10^-19 C. Total charge = 50 * 1.6*10^-19 = 80*10^-19 C.
Q3. Robert Millikan balanced charged oil drops against gravity in his apparatus; what quantity did he determine?
- A.the speed of cathode rays
- B.the charge of a single electron
- C.the mass of the nucleus
- D.the number of atoms in a drop
Answer: B. the charge of a single electron
By balancing the electric force on oil drops against gravity, Millikan found the electron's charge, 1.6*10^-19 C.
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