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3 years ago

Arrange the events in the life of a star in the correct order.

Chemistry

1 answer:

tatiyna3 years ago

3 0

Answer:

1. The temperature increases in the center of a nebula, and nuclei begin to fuse.

2. As the nuclear fusion sets off a chain reaction, the nebula gets hotter and brighter and turns into a star.

3. The star stays in the main sequence stage for a long time.

4. The star runs out of hydrogen and turns into a planetary nebula or a supernova, depending on its mass.

5. Heavy elements are created when the supernova explodes.

6. All that remains of the star now is the core. In some cases, the star turns into a black hole.

Explanation:

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Which of the following is unchanged at the end of the CNO cycle?

Musya8 [376]

Answer:

The correct option is: A. carbon-12

Explanation:

The CNO cycle, the abbreviation for the carbon-nitrogen-oxygen cycle, is a catalytic cycle by which the stars produce helium from elemental hydrogen, via a series of nuclear fusion reactions.

This cycle involves the fusion of four protons with carbon ( $_{6}^{12}\textrm{C}$ ), nitrogen isotope ( $_{7}^{13}\textrm{N}$ ), and oxygen isotope ( $_{8}^{15}\textrm{O}$ ), to give an alpha particle and two electron neutrinos and positrons.

The reaction involves the regeneration of carbon ( $_{6}^{12}\textrm{C}$ ) nucleus in the last step.

$_{6}^{12}\textrm{C}$ → $_{7}^{13}\textrm{N}$ → $_{6}^{13}\textrm{C}$ → $_{7}^{14}\textrm{N}$ → $_{8}^{15}\textrm{O}$ → $_{7}^{15}\textrm{N}$ → $_{6}^{12}\textrm{C}$

3 0

3 years ago

In the equilibrium constant expression for the reaction below what is the correct exponent for N2O4?

irga5000 [103]

As we have the balanced reaction equation is:

N2O4 (g) ↔ 2NO2(g)

from this balanced equation, we can get the equilibrium constant expression

KC = [NO2]^2[N2O4]^1

from this expression, we can see that [NO2 ] is with 2 exponent of the stoichiometric and we can see that from the balanced equation as NO2
is 2NO2 in the balanced equation.

and [N2O4] is with 1 exponent of the stoichiometric and we can see that from the balanced equation as N2O4 is 1 N2O4 in the balanced equation.

∴ the correct exponent for N2O4 in the equilibrium constant expression is 1

7 0

4 years ago

What is the oh of a solution with a ph of 9.8

Veseljchak [2.6K]

It would be 4.2, hope this helps.

4 0

3 years ago

a physical property can be observed while the substance remains the same in its chemical composition. true false

sweet [91]

While the material retains its chemical makeup, the physical property may be examined. The given statement is true.

The matter can undergo variations in physical or chemical properties. The physical changes of a matter occur when the matter undergoes changes in its physical properties like changes in the state of matter, weight, color, etc.

But the chemical composition of matter will remain constant if it undergoes a physical change. Whereas in chemical change, the matter undergoes a change in the composition of the substance but there will be no change in the physical properties.

Hence, The assertion is correct in that physical properties can be seen while the substance's chemical makeup stays constant.

To learn more about physical and chemical change, visit: brainly.com/question/21509240

#SPJ4

8 0

1 year ago

At equilibrium, ________. At equilibrium, ________. all chemical reactions have ceased the rate constants of the forward and rev

balandron [24]

Answer:

<em>At equilibrium, the rate of the forward, and the reverse reactions are equal.</em>

Explanation:

In an equilibrium chemical reaction, the rate of forward reaction, is equal to the rate of reverse reaction. Note that the reactions does not cease at equilibrium, but rather, the reactants are converted to product, at the same rate at which the product is also being converted into the reactants in the reaction. When chemical equilibrium is reached, a careful calculation of the value of equilibrium constant is approximately equal to 1.

NB: If the value of equilibrium constant is far far greater than 1, then the reaction will favors more of the forward reaction, and if far far less than 1, the reaction will favor more of the reverse reaction.

6 0

3 years ago