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Annette [7]
2 years 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]2 years 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]2 years 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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1. A student performs a reaction in a beaker by reaction silver nitrate with one long copper wire. The student’s thermometer cha
stiv31 [10]

Explanation:

The observation of student was that thermometer reading changed from 27°C to 35°C which indicates that temperature of the beaker solution rose after reaction due to release of heat during reaction as a product.

Those chemical reactions which gives heat energy as a product into their surrounding are categorized as exothermic reactions. During the course of these reaction temperature of the surroundings also increased.

So, this means that reaction between silver nitrate and copper wire is an exothermic reaction.

Three ways that the student could speed up the reaction :

  • By adding catalyst to the reaction.
  • By decreasing the temperature.
  • By increasing the concentration of silver nitarte solution.
3 0
2 years ago
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Which of the following phrases describes valence electrons?
kykrilka [37]

Answer:

C

Explanation:

because valence electrons are located at the last energy level

7 0
2 years ago
Two nonpolar organic liquids, hexane (C6H14) and heptane (C7H16), are mixed. Do you expect ΔHsoln to be a large positive number,
Aliun [14]

Answer:

ΔH of solution is expected to be close to zero.

Explanation:

When we mix two non polar organic liquids like hexane and heptane,the resulting mixture formed is an ideal solution.An ideal solution is formed when the force of attraction between the molecules of the two liquids is equal to the force of attraction between the molecules of the same type.

For instance if liquids A and B are mixed,

F_{A-A} = F_{B-B} = F_{A-B}

Hence the condition before and after mixing remains unchanged.

Since enthalpy change is associated with inter molecular force of attraction the enthalpy change for ideal solution is zero.

More examples of ideal solutions are:

1. Ethanol and Methanol

2. Benzene and Toluene

3. Ethyl bromide and Ethyl iodide

5 0
2 years ago
What is the identity of a sample that has a mass of 2.44 g and a volume of 0.34 cm3?
borishaifa [10]
The answer would be zinc
3 0
2 years ago
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In fractional distillation, liquid can be seen running from the bottom of the distillation column back into the distilling flask
shepuryov [24]

Answer:

substances with a higher boiling point are returning back to the flask which allows another substances with the specific context temperature (lower boiling point) to boil over and be purified.

Explanation:

The reason it happens because the lower boiling point substance vaporizes and crosses over while the other substance is waiting for its boiling point to reach

7 0
2 years ago
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