Many people believe that the atomic number of the atom is the number of electrons in the atom. Describe when this is the case
2 answers:
Answer: The atomic number of the atom is the number of electrons in the atom only when the atom is neutral.
Explanation: For a neutral atom, the number of positive charges is equal to the number of negative charges and thus the atomic number is equal to the number of electrons or the number of protons.
But for a positive and a negative ion, the electrons are lost and gained respectively by that element and thus the number of electrons are not equal to the number of protons. Now atomic number is equal to the number of protons only. The number of electrons = number of protons - charge.
Example: For sodium , the atomic number is 11 and it has 11 electrons.
For sodium ion , the atomic number is 11 but the number of electrons = (11-1) = 10.
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Answer:
The frequency of sound heard by the boy is 1181 Hz.
Explanation:
Given that,
Frequency of sound from alarm
Speed = -8.25 m/s
Negative sign show the boy riding away from the car
Speed of sound = 343
We need to calculate the heard frequency
Using formula of frequency
Where, = frequency of source
= speed of observer
= speed of source
= speed of sound
Put the value into the formula
here, source is at rest
Hence, The frequency of sound heard by the boy is 1181 Hz.