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Q7. Who proposed the quantum mechanical model of the atom, incorporating wave-particle duality?
a) Max Planck
b) Albert Einstein
c) Louis de Broglie
d) Erwin Schrödinger
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Correct Answer: d) Erwin Schrödinger
Explanation: Erwin Schrödinger proposed the quantum mechanical model of the atom in 1926. This model describes electrons as waves rather than particles, incorporating the wave-particle duality concept. It is based on mathematical equations known as wave functions.
Q8. The Heisenberg Uncertainty Principle states that:
a) It is impossible to precisely measure both the position and momentum of a particle simultaneously
b) Electrons can exist in multiple places at once
c) Energy and time are inversely related
d) The speed of light is constant in all reference frames
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Correct Answer: a) It is impossible to precisely measure both the position and momentum of a particle simultaneously
Explanation: The Heisenberg Uncertainty Principle, formulated by Werner Heisenberg, states that it is impossible to simultaneously precisely measure both the position and momentum (or velocity) of a particle. This principle arises due to the wave-particle duality of matter.
Q9. Who discovered the neutron, an electrically neutral subatomic particle?
a) James Chadwick
b) Marie Curie
c) Ernest Rutherford
d) Enrico Fermi
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Correct Answer: a) James Chadwick
Explanation: James Chadwick discovered the neutron in 1932 through his experiments involving the bombardment of beryllium atoms with alpha particles. He observed the emission of a previously unknown neutral particle, which he identified as the neutron.
Q10. The modern atomic theory states that atoms are composed of:
a) Protons, neutrons, and electrons
b) Protons and electrons only
c) Neutrons and electrons only
d) Protons only
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Correct Answer: a) Protons, neutrons, and electrons
Explanation: The modern atomic theory, based on experimental evidence and advancements in physics, states that atoms are composed of three subatomic particles: protons (positively charged), neutrons (electrically neutral), and electrons (negatively charged). These particles form the building blocks of matter.