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3 years ago

15

How many neutrons does element X have if its atomic number is 23 and its mass number is 90?

2 answers:

givi [52]3 years ago

4 0

Answer:

67

Explanation:

- The atomic number (Z) of an atom is equal to the number of protons in the nucleus

- The mass number (A) of an atom is equal to the sum of protons and neutrons in the nucleus

Therefore, calling p the number of protons and n the number of neutrons, for element X we have:

Z = p = 23

A = p + n = 90

Substituting p=23 into the second equation, we find the number of neutrons:

n = 90 - p = 90 - 23 = 67

Zina [86]3 years ago

4 0

<h2>Answer:</h2>

<u>The number of neutrons is </u><u>67</u>

<h2>Explanation:</h2>

As we know that the atomic number is the number of protons. If we subtract the atomic number from the mass number, we can actually find the number of neutrons.

So

Number of neutrons = Mass number - atomic number

Neutrons = 90 - 23 = 67

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Suppose a light source is emitting red light at a wavelength of 700 nm and another light source is emitting ultraviolet light at

klasskru [66]

Answer:

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Energy of a photon is given by

$E=h\nu\\\Rightarrow E=h\dfrac{c}{\lambda}$

Let $\lambda_1$ = 700 nm

$\lambda_2=350\\\Rightarrow \lambda_2=\dfrac{\lambda_1}{2}$

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