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Ludmilka [50]
4 years ago
12

Which of these pairs of elements have the same number of valence electrons?

Chemistry
1 answer:
topjm [15]4 years ago
3 0
Pairs of elements that have the same number of valence electrons are:
sodium (Na) and potassium (K).
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From 1962 until 1981 pennies were made from 95% copper and 5% zinc and had a mass of 3.1 g. Starting in 1982, pennies have been
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2.7724 g

Explanation:

Mass of pre- 1892 pennies = 3.1 g

Abundance = 45.4 %

Mass of post 1892 pennies = 2.5 g

Abundance = 100 - 45.4 = 54.6 %

The average mass is given as = ( 3.1 g   *  45.4 / 100)  +  (2.5g  *  54.6 / 100)

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8 0
3 years ago
A mixture of iron and sulfur can be separated by A.magnetic attraction
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6 0
3 years ago
What is the mass of 5.00 moles of KaS04?
Varvara68 [4.7K]

Answer: D

Explanation:

I assume you meant \text{K}_{2}\text{SO}_{4}.

  • The atomic mass of potassium is 39.0983 g/mol.
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  • The atomic mass of oxygen is 15.9994 g/mol.

So, the formula mass of potassium sulfate is 2(39.0983)+32.065+4(15.9994)=174.2592 g/mol.

So, 5.00 moles have a mass of (5.00)(174.2592), which is about <u>870 g</u>

7 0
2 years ago
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