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olga_2 [115]
2 years ago
5

How can models demonstrate theories of our expanding universe?​

Chemistry
1 answer:
Scilla [17]2 years ago
7 0

Answer:

Explanation:Puesto que la energía causante de la aceleración del espacio-tiempo no ha podido ser observada en forma directa, se ha dado en llamarla energía oscura. Dos candidatos teóricos que podrían hacer las veces de esta energía son una constante cosmológica no igual a cero (que pudo haber causado la inflación cósmica) y una energía repulsiva más general llamada quintaesencia.

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. How many grams of Na2SO4 are required to make 2700 mL of a 2.0 M solution?
ratelena [41]

Answer:

Explanation:

From the net ionic equation

Ba2+(aq) + SO42-(aq) ==> BaSO4(s) we see that 1 mole Ba2+ reacts with 1 mole SO42- to -> 1 mol BaSO4

Find moles of Ba2+ used: 0.250 moles/L x 0.0323 L = 0.008075 moles Ba2+

Find moles SO42- present: 0.008075 moles Ba2+ x 1 mol SO42-/1 mol Ba2+ = 0.008075 mol SO42-

Find mass of Na2SO4 present: 0.008075 mol SO42- x 1 mol Na2SO4/1 mol SO42- x 142.04 Na2SO4/mole = 1.14698 g = 1.15 g Na2SO4 (to 3 significant figures)

6 0
2 years ago
Read 2 more answers
What is molecular formula
Mazyrski [523]

Answer:a formula giving the number of atoms of each of the elements present in one molecule of a specific compound.

Explanation:

3 0
3 years ago
Read 2 more answers
PLEASE HELP ME!!! NEED THE ANSWER FAST! WILL CHOOSE THE BRAINLIEST!!!
Vlad [161]
Remember that a cation will be smaller than its neutral atom, and an anion will be larger than its neutral atom. This would automatically eliminate answer choices A and D.

Also keep in mind that atomic radii decreases from left to right as you move along a periodic table. It also decreases from bottom up. 
Atomic radii increases as you move from right to left and as you go from up to down.

As bromine is higher up in the periodic table than Iodine, it would have a smaller radius. Iodine would have a larger radius.

The correct answer is B. Br
8 0
3 years ago
Which type of drug commonly marketed to consumers does not require a prescription?
Nimfa-mama [501]
C. pain reliever
ex. tylenol, aleve, etc.
7 0
2 years ago
How many grams of F− must be added to a cylindrical water reservoir having a diameter of 2.02 × 102 m and a depth of 87.32 m?
aksik [14]

Complete Question:

To aid in the prevention of tooth decay, it is recommended that drinking water contain 0.800 ppm fluoride. How many grams of F− must be added to a cylindrical water reservoir having a diameter of 2.02 × 102 m and a depth of 87.32 m?

Answer:

2.23x10⁶ g

Explanation:

The concentration of the fluoride (F⁻) must be 0.800 ppm, which is 0.800 parts per million, so the water must have 0.800 g of F⁻/ 1000000 g of the solution. The density of the water at room temperature is 997 kg/m³ = 997x10³ g/m³. So, the concentration of the fluoride will be:

0.800 g of F⁻/ 1000000 g of the solution * 997x10³ g/m³

0.7976 g/m³

The volume of the reservoir is the volume of the cylinder: area of the base * depth. The base is a circumference, which has an area:

A = πR², where R is the radius = 1.01x10² m (half of the diameter)

A = π*(1.01x10²)²

A = 32047 m²

The volume is then:

V = 32047 * 87.32

V = 2.7983x10⁶ m³

The mass of the F⁻ is the concentration multiplied by the volume:

m = 0.7976 * 2.7983x10⁶

m = 2.23x10⁶ g

8 0
3 years ago
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