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3 years ago

An atom has a mass number of 9 and 5 neutrons. What is its atomic number? A 19 B. 14 O c.4 D. 11 SN

Chemistry

2 answers:

nika2105 [10]3 years ago

5 0

Answer:

$\boxed {\boxed {\sf C. \ 4}}$

Explanation:

First, define some important terms.

Mass number: the sum of the nucleons (protons and neutrons)
Atomic number: the number of protons

We know the mass number is 9. So, the sum of protons and neutrons is 9.

$mass \ number =9$

$protons + neutrons = 9$

We also know the atoms has 5 neutrons. Therefore, the rest must be protons.

$protons + 5 \ neutrons =9$

Subtract the 5 neutrons from the overall mass number of 9.

$protons = 9- 5 \ neutrons \\$

$protons=4$

There are 4 protons, so the atomic number is also <u>4</u>. This atom is beryllium.

butalik [34]3 years ago

4 0

Answer:

C. 4

Explanation:

the mass is the number of neutrons and Protons. so if you have 5 neutrons that means the rest are Protons... and the number of Protons is the Atomic number meaning the Element number... Beryllium is the element :)

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Atomic mass is basically the number of protons and neutrons present in an atom.

Atomic number is the number of protons present in an atom.

So, in isotopes the number of protons are same but the number of neutrons vary due to which atomic masses also vary.
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An atom has a mass number of 9 and 5 neutrons. What is its atomic number? A 19 B. 14 O c.4 D. 11 SN​

An atom has a mass number of 9 and 5 neutrons. What is its atomic number? A 19 B. 14 O c.4 D. 11 SN