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3 years ago

_____________________ held that all matter is made up of four “elements”— earth, air, fire, and water.

Chemistry

1 answer:

Novosadov [1.4K]3 years ago

4 0

Answer:

Democritus

Explanation:

He spoke about matter was made of tiny particles which moved in empty space

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Implement pollution reduction strategies that are needed to clean up the river ????

miss Akunina [59]

Answer:

* Properly dispose of hazardous household items.

* Reduce or eliminate use of fertilizers and chemical herbicides and pesticides.

* Make an appointment to service your septic system

Landscape with native plants.

* Eliminate bare spots in your yard.

* Make a rain garden.

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2 years ago

19)Calculate the number of moles of Al2O3 that are produced when 15 mol of Fe is produced

Margarita [4]

Answer:

Explanation:

Calculate the number of moles of Al2O3 that are produced when 15 mol of Fe is produced

in the following reaction.

C) 45 mol

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3 years ago

A boy swings a rubber ball attached to a string over his head in a horizontal, circular path. The piece of string is 1.15 m long

gregori [183]

Answer:

v = 16.49 m/s

Explanation:

Given that,

Length of the string, l = 1.15 m

The ball makes 137 complete turns each minute.

We know that, 1 turn = 6.28 rad

137 turns = 860.79 rad

1 min = 60 s

$\omega=\dfrac{860.79\ rad}{60\ s}\\\\=14.34\ rad/s$

We need to find the tangential velocity of the ball. It can be given by

$v=r\omega\\\\=1.15\times 14.34\\\\v=16.49\ m/s$

So, the tangential velocity of the ball is 16.49 m/s.

5 0

3 years ago

Water-soluble vitamins: a. often result in toxicities b. are easily excreted in the urine c. are stored in body tissues to a lar

enyata [817]

Answer: Option (b) is the correct answer.

Explanation:

Vitamins which are soluble in water are known as water-soluble vitamins. And, vitamins which remain insoluble in water are known as water-insoluble vitamins.

Water-soluble vitamins are able to be easily excreted by the human body through urine. For example, vitamin C and vitamin B-complex are water soluble vitamins.

Thus, we can conclude that water-soluble vitamins are easily excreted in the urine.

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3 years ago

An unknown amount of mercury (II) oxide was decomposed in the lab. Mercury metal was formed and 5.20 L of oxygen was released at

Yakvenalex [24]

Answer:

68.3g

Explanation:

1. Word equation:

mercury(II) oxide → mercury + oxygen

2. Balanced molecular equation:

2HgO → 2Hg + O₂(g)

3. Mole ratio

Write the ratio of the coefficients of the substances that are object of the problem:

$2molHgO/1molO_2$

4. Calculate the number of moles of O₂(g)

Use the equation for ideal gases:

$pV=nRT\\\\\\n=\dfrac{pV}{RT}\\\\\\n=\dfrac{0.970atm\times5.20L}{0.08206atm.L/K.mol\times 390.0K}\\\\\\n=0.1576mol$

5. Calculate the number of moles of HgO

$\dfrac{2molHgO}{1molO_2}\times 0.1576molO_2=0.315molHgO$

6. Convert to mass

mass = # moles × molar mass

molar mass of HgO: 216.591g/mol

mass = 0.315mol × 216.591g/mol = 68.3g

7 0

3 years ago