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Annette [7]
1 year ago
7

Which statements describe how stars are born? Check all that apply. Stars are born in clouds of gas and dust called nebulas. The

gas and dust are pulled together by gravity. If the cloud that is pulled together has enough mass, a red giant is formed. The pulled-together cloud collapses and becomes hot and dense. Heat and pressure cause nuclear fusion, which signals the birth of a star.
Chemistry
2 answers:
zhannawk [14.2K]1 year ago
8 0

Answer:

1.Stars are born in clouds of gas and dust called nebulas.

2.The gas and dust are pulled together by gravity.

4.The pulled-together cloud collapses and becomes hot and dense.

5.Heat and pressure cause nuclear fusion, which signals the birth of a star.

Explanation:

prohojiy [21]1 year ago
6 0

Answer: 1.Stars are born in clouds of gas and dust called nebulas.

2.The gas and dust are pulled together by gravity.

3.Heat and pressure cause nuclear fusion, which signals the birth of a star.

Explanation:

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If a large marshmallow has a volume of 2.75 in3 and density of 0.242 g/cm3, how much would it weigh in grams? 1 in3=16.39 cm3.
Anestetic [448]
<span>
•   </span>Volume of the marshmallow:

V = 2.75 in^3          (but, 1 in^3 = 16.39 cm^3)

V = 2.75 × 16.39 cm^3

V = 2.75 × 16.39 cm^3

V = 45.0725 cm^3


•   Density:

d = 0.242 g/cm^3


<span>•  </span>Mass:

m = d × V

m = (0.242 g/cm^3) × (45.0725 cm^3)

m = (0.242 g/cm^3) × (45.0725 cm^3)

m = 10.907545 g

m ≈ 10.9 g   <——<span>—  this is the answer.


I hope this helps. =)
</span>
4 0
2 years ago
In 200 g of a concentrated solution of 70.4 wt% nitric acid (r = 1.41 g/mL, FW(HNO3) = 63.01 g/mol), how many grams of water are
mars1129 [50]

Answer:

59.2 grams

Explanation:

We are given that 70.4% of the weight of the total 200 g of the concentration is made up of nitric acid, the remaining information is not required to solve the problem. Since water and nitric acid are the only components of the solution, the total weight of water is given by:

W = 200*(1-0.704)\\W=59.2\ g

There are 59.2 grams of water in this solution.

5 0
2 years ago
The mass of radium-226 in a sample is found to have decreased from 45.00g to 5.625g in a period of 4800 years.From this informat
yan [13]

Answer:

Half life = 1600 years

Explanation:

Given data:

Total mass of sample = 45.00 g

Mass remain = 5.625 g

Time period = 4800 years

Half life of radium-226 = ?

Solution:

First of all we will calculate the number of half lives passes,

At time zero 45.00 g

At first half life = 45.00 g/ 2= 22.5 g

At 2nd half life = 22.5 g/ 2 = 11.25 g

At 3rd half life = 11.25 g/ 2= 5.625 g

Half life:

Half life = Time elapsed / number of half lives

Half life = 4800 years / 3

Half life = 1600 years

4 0
1 year ago
Grignard reagents are air-and moisture-sensitive. List at least threereactants, solvents, and/or techniques that were utilized i
Evgesh-ka [11]
<h2>Diethylether (DTH) andTetrahydrofuran (THF).</h2>

Explanation:

  • Grignard reactions reacts with water forming alkanes.
  • The water present causes the reagent to decompose rapidly.      
  • So, the solvents which are utilized in the experimental procedure to minimize exposure of the grignard reagents to air and/ormoisture are solvents such as anhydrous diethyl ether or tetrahydrofuran(THF), poly(tetramethylene ether) glycol (PTMG).
  • The reason for the use of these solvents is the oxygen present in these solvents stabilizes the magnesium reagent.
  • THF (Tetrahydrofuran) is a stable compound.
4 0
2 years ago
Three test tubes contain white crystalline organic solids A, B, and C, each of which melts at 149-150 degrees C. A 50-50 mixture
Digiron [165]

Answer:

The mixture of B and C will melt as 130 - 139 ºC.

Explanation:

If the melting point (130 - 139 ºC) of a mixture of A and B is lower than the pure substances that is 149 - 150 ºC that means that one of these susbtances is an impurity because reduces the melting point.

If the melting point of the mixture of A and C is the same as the pure substances, we can deduce that they are the same substances, also because the melting point when a substance is pure is just 1 or 2 ºC like in this case.

So in a Mixture of B and C is going to be like the first case of the mixture among A and B, because the B substance is the impurity.

3 0
1 year ago
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