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julia-pushkina [17]
2 years ago
15

In 1687, ___ explained that gravitational forces hold the solar system together.

Chemistry
2 answers:
elena55 [62]2 years ago
5 0
The answer is A. Newton
Nimfa-mama [501]2 years ago
3 0
Newton ,perhaps as many other originations  use it as a gravitational law
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How many mL of alcohol are in 240 mL of 95.0% alcohol solution?
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To work it out, you divide 240 by 100 to work out 1% of it, then multiply that by 95 to work out 95% of it. So
(240/100) * 95 = 228mL
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2 years ago
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The half-life of cesium-137 is 30 years. Suppose we have a 200-mg sample. (a) Find the mass that remains after t years.
scZoUnD [109]

Given:

Half life(t^ 1/2) :30 years

A0( initial mass of the substance): 200 mg.

Now we know that

A= A0/ [2 ^ (t/√t)]

Where A is the mass that remains after t years.

A0 is the initial mass

t is the time

t^1/2 is the half life

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A= [200/ 2^(t/30) ] mg


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5 0
3 years ago
Draw the lewis structure for bef2 in the box at the right, including lone pairs.
Kamila [148]

Answer :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and the unpaired electrons present in the molecule.

The given molecule is, BeF_2

Beryllium has '2' valence electrons and fluorine has '7' valence electrons. Beryllium is the central atom and fluorine is the terminal atom.

Total number valence electrons in BeF_2 = 2 + 2(7) = 16

According to the Lewis-dot structure, there are '4' number of bonding electrons and 12 number of non-bonding electrons (lone-pair).

The Lewis-dot structure is shown below.

3 0
2 years ago
A force that slows down airplanes
Advocard [28]
I  can think of 2 off the top of my head first is friction and second is gravity
3 0
3 years ago
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Give the formula for an ionic compound formed from each pair of ions
Vera_Pavlovna [14]

Please, find the complete question in the picture attached.

Answer:

1. Na₂O

2. AlF₃

3. MgO

4. Ca₃P₂

Explanation:

1. Na⁺ and O²⁻

An ionic compound will be formed when two ions of opposite charge attract each other.

The positive ion is called cation and the negative ion is called anion.

Thus, every ionic compound has a cation and an anion electrostatically bonded.

The ions must combine in a proportion that genders a neutral compound: so you must have as many cations as negative charge has one anion and as many anions as positive charge has one cation.

This is, if the cation has charge +x, there will be x anions, and if the anion has charge -y, there will be y cations.

Simbolically:

Cation:A^{+x}\\ \\ Anion:B^{-y}\\ \\ Compound:A_yB_x

As you see, the subscripts for each element in the chemical formula are obtained by the exchage of the charges of the ions.

Then, for Na⁺ and O²⁻, the subscript for Na will be 2 and the subscript for O will be 1; and the formula of the ionic compound formed by this pair ot ions is:

  • Na₂O

2. Al³⁺ and F⁻

  • The subscript of Al will be 1 (because the F ion has charge 1-, and the subscript of F will be 3 (because the Al ion has charge +3).

Thus the ionic compound formed by this pair of ions is:

  • AlF₃

3. Mg²⁺ and S²⁻

  • The charge 2+ from Mg atom wil become the subscript 2 of S atom, and the charge 2- will become the subscript 2 of Mg atom:

That results in the formula: Mg₂S₂

Except for some special compounds, the chemical formula is simplified, dividing by the least common denominator. In this case, that means that the two 2 subscripts are simplified to 1, and the final chemical formula for the ionic compound formed by this pair of ions is:

  • MgO

4. Ca²⁺ and P³⁻

  • The charge 2+ from Ca will become subscript 2 for P and the charge 3- whill become subscript 3 for Ca.

Hence, the ionic compound formed by these two ions is:

  • Ca₃P₂

7 0
2 years ago
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