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Rina8888 [55]
3 years ago
14

What do astronomers use to calculate the age of the universe? Check all that apply. dark energy the age of rocks on Earth the ag

e of the oldest stars patterns of background radiation how fast distant galaxies are moving away from us
Chemistry
2 answers:
Hitman42 [59]3 years ago
4 0

The answers are:

The age of the oldest stars

How fast distant galaxies are moving away from us

Patterns of background radiation

Using these techniques, and using the Big Bang as reference point, astronomers estimate that the universe may be approximately 12 billion years old.


Likurg_2 [28]3 years ago
4 0

the age of the oldest stars

patterns of background radiation

how fast distant galaxies are moving away from us

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What is the different between a mixture and a compound?
krek1111 [17]
A compound is 2 or more substances chemically combined, mixtures arent

4 0
3 years ago
Given a magnesium value of 4.5mg/dL what is the result in SI units? gram atomic weight of Mg = 24
lord [1]

Explanation:

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7 0
3 years ago
10.000g of boron (B) combines with hydrogento form 11.554g of a pure compound. What is the empirical formula of this compound?
Citrus2011 [14]

Answer:

B3H5

Explanation:

The law of conservation of mass states that matter in an closed system is neither created nor destroyed by physical transformations or chemical reactions but changes from one form to the other.

That is, the sum of masses of the reactants = The sum of masses of the product

10.00g of Boron + x grams of Hydrogen = 11.55g of the product

Mass of hydrogen = 11.55 - 10.00 = 1.55g

Molar mass of Boron = 10.811g

Molar mass of Hydrogen = 1.00784g

Number of moles of Boron = (mass of Boron)/(molar mass of Boron) = 10/10.811 = 0.9249 mols

Number of moles of Hydrogen = (mass of Hydrogen)/(molar mass of Hydrogen) = 1.55/1.00784 =1.5379mols

0.9249 mols of Boron combines with 1.5379mols of Hydrogen

Dividing both sides mols by 0.9249 gives

1 mole of Boron combines with 1.66266 mols of Hydrogen

Converting 1.66266 to fractions we have 1.66266 approximately 5/3

or 1 mole of Boron combines with 5/3 moles of Hydrogen

Multiplying both sides by 3 we have

3 moles of Boron combines with 5 moles of Hydrogen

Molecular formula of the compound is

B3H5

4 0
3 years ago
A student wrote The Following hypothesis if more salt is added to a hypothesis
Hatshy [7]

Answer:

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Explanation:

4 0
3 years ago
You find a compound composed only of element X and chlorine and you know that the compound is 13.10% X by mass. Each molecule of
8_murik_8 [283]

Answer:

Explanation:

So, the formula for the compound should be:

XCl_{6}

Now we assume that we have 1 mol of substance, so we can make calculations to know the molar mass of element X, as follows:

M_{Cl}=35.45g/mol\\

So we have that 6 moles weight 212.7g, and we can make a rule of three to know the weight of compound X:

212.7g\rightarrow 86.9\%\\x\rightarrow 13.1\%\\\\x=\frac{212.7g*13.1}{86.9} =32.06g

As we used 1 mol, we know that the molar mass is 32.06g/mol

So the element has a molar mass of 32.06 g/mol and an oxidation state of +6, with this information, we can assure that the element X is sulfur, so the compound is SCl_{6}

8 0
3 years ago
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