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Physics Past Questions and Answers

Waec Physics Questions

Question 996:

An atom is normally electrically neutral because the

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A Number of electrons is equal to the number of protons
B Number of electrons is equal to the number of neutrons
C Number of protons is equal to the number of neutrons
D Electrons of the atom are buried deeply in the nucleus

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Question 997:

In which of the following devices is the principle of photoelectric effect not applicable?

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A Close-circuit television camera
B Burglar alarm
C Solar cells
D Periscope

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Question 998:

Which of the following statements about X-rays is not correct? They

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A Are electromagnetic waves
B Can be used to study crystal lattice
C Can destroy living cells
D Are produced from the nucleus of an atom

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Question 999:

A radioactive substance has a half-life of 3 days. If a mass of 1.55g of this substance is left after decaying for 15 days, determine the original value of the mass

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A 49.6g
B 37.2g
C 24.8g
D 12.4g

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Question 1000:

Which of the following representations is correct for an atom X with 28 electrons and 30 neutrons?

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A \(^{30}_{28} X\)
B \(^{28}_{30} X\)
C \(^{58}_{30} X\)
D \(^{58}_{28} X\)

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