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2 years ago

Which statement accurately describes dark matter?

Chemistry

2 answers:

pickupchik [31]2 years ago

6 0

Yes it have to be C

Mandarinka [93]2 years ago

5 0

Answer:

C. It does not emit electromagnetic radiation.

Explanation:

Right now, Dark Matter is only a theory. Scientist proposed this to counter some of the strange phenomenon with matter in space.

Scientists know little about dark matter. Some say it's one of the driving forces of the universe. Currently, scientists have no way of measuring or identifying dark matter.

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A sample of krypton has a volume of 6.00 L, and the pressure is 0.960 atm. If the final temperature is 55.0°C, the final volume

MissTica

193.38 K was the initial temperature of the krypton.

Explanation:

Data given:

Initial volume of the krypton gas = 6 litres

initial pressure of the krypton gas = 0.960 atm

initial temperature of the krypton gas = ?

final volume of the krypton gas = 7.70 litres

final pressure of the Krypton gas = 1.25 atm

final temperature of the krypton gas = 55 degrees or 273.25+55 = 323.15 K

Applying the Combined Gas Laws:

$\frac{P1V1}{T1} = \frac{P2V2}{T2}$

Rearranging the equation:

T1 = $\frac{P1V1T2}{P2V2}$

Putting the value in the equation:

T1 = $\frac{0.960 X 6 X 323.15}{1.25 X 7.70}$

T1 = 193.38 K

Initial temperature of the krypton gas is 193.78 K

5 0

2 years ago

What is the theoretical yield of CuS when 31.8g of Cu(s) is heated with 50.0g of S? (Asume only CuS is produced in the reaction)

liberstina [14]

Answer:

The answer to your question is: 83.9 %

Explanation:

Data

Cu = 31.8 g

S = 50 g

CuS = 40 g

yield = ?

Equation

Cu + S ⇒ CuS

MW Cu = 64 g

MW S = 32 g

MW CuS = 96 g

Ratio (theoretical/experimental)

Experimental 50/31.8 = 1.57

Theoretical 32/64 = 0.5 limiting reactant Cu

64 g of Cu ------------------ 96 g of CuS

31.8 g ------------------- x

x = (31.8 x 96) / 64

x = 47.7 g of CuS

% yield = (40/47.7) x 100

= 83.9 %

6 0

2 years ago

Read 2 more answers

How many grams of antifreeze C2H4(OH)2 would be required per 500 g of water to prevent the water from freezing at a temperature

Wewaii [24]

Answer:

333.7 g.

Explanation:

The depression in freezing point of water (ΔTf) due to adding a solute to it is given by: ΔTf = Kf.m.

Where, ΔTf is the depression in water freezing point (ΔTf = 20.0°C).

Kf is the molal freezing point depression constant of the solvent (Kf = 1.86 °C/m).

m is the molality of the solution.

∴ m = ΔTf/Kf = (20.0°C)/(1.86 °C/m) = 10.75 m.

molaity (m) is the no. of moles of solute per kg of the solvent.

∵ m = (no. of moles of antifreeze C₂H₄(OH)₂)/(mass of water (kg))

∴ no. of moles of antifreeze C₂H₄(OH)₂ = (m)(mass of water (kg)) = (10.75 m)(0.5 kg) = 5.376 mol.

∵ no. of moles = mass/molar mass.

∴ mass of antifreeze C₂H₄(OH)₂ = no. of moles x molar mass = (5.376 mol)(62.07 g/mol) = 333.7 g.

5 0

2 years ago

Magnesium reacts with a certain element to form a compound with the general formula MgX. What would the most likely formula be f

Rama09 [41]

Answer:

K2X

Explanation:

Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.

MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.

Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1

Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X

4 0

2 years ago

Be sure to answer all parts. For each reaction, find the value of ΔSo. Report the value with the appropriate sign. (a) 3 NO2(g)

Liono4ka [1.6K]

Answer:

a. -268.13 J/K

b. -279.95 J/K

c. + 972.59 J/K

Explanation:

The value of the change in entropy (ΔS°) can be calculated by:

ΔS° = ∑n*S° products - ∑n*S° reactants, where n is the stoichiometric number of moles.

The values of S° for each substance can be found on a thermodynamic table.

a. 3NO2(g) + H2O(l) → 2HNO3(l) + NO(g)

S°, NO2(g) = 240.06 J/mol.K

S°, H2O(l) = 69.91 J/mol.K

S°, HNO3(l) = 155.60 J/mol.K

S°, NO(g) = 210.76 J/mol.K

ΔS° = (210.76 + 2*155.60) - (3*240.06 + 69.91)

ΔS° = -268.13 J/K

b. N2(g) + 3F2(g) → 2NF3(g)

S°, N2(g) = 191.61 J/mol.K

S°, F2(g) = 202.78 J/mol.K

S°, NF3(g) = 260.0 J/mol.K

ΔS° = (2*260.0 ) - (191.61 + 3*202.78)

ΔS° = -279.95 J/K

c. C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(g)

S°, C6H12O6(s) = 212 J/mol.K

S°, O2(g) = 205.138 J/mol.K

S°, CO2(g) = 213.74 J/mol.K

S°, H2O(g) = 188.83 J/mol.K

ΔS° = (6*213.74 + 6*188.83) - (212 + 6*205.138)

ΔS° = +972.59 J/K

3 0

2 years ago

Which statement accurately describes dark matter?￼

Which statement accurately describes dark matter?