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musickatia [10]
3 years ago
14

The atomic symbol for beryllium 9/4be indicates that the

Chemistry
2 answers:
Crazy boy [7]3 years ago
8 0

<u>Answer:</u>  b) Mass number is 9.

<em>The atomic symbol for beryllium 9/4 be indicates that the mass number is 9.</em>

<u>Explanation:</u>

Beryllium metal, Be was placed in second group and second period of periodic table. It occur as solid at 20°C. Its atomic number is 4 and the mass number is 9.

<em>Atomic number, Z = number of proton or number of electrons in the atom. </em>

<em>Mass number = Atomic no + number of neutrons in the atomic nucleus.</em>

<em>So the atomic symbol for beryllium is indicated as mass number of 9.</em>

MrMuchimi3 years ago
4 0
I believe the answer is B)
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Answer:

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Explanation:

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M = n / V

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Moles is denoted by given mass divided by the molecular mass ,  

Hence ,  

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From the question ,

w = given mass of NaCl = 7.2 g

As we know , the molecular mass of NaCl = 58.5 g/mol

Moles is calculated as -

n = w / m  =  7.2 g / 58.5 g/mol = 0.123 mol

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3 years ago
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