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lisov135 [29]
3 years ago
15

Explain how temperature and mass affect the appearance of stars

Chemistry
1 answer:
Nesterboy [21]3 years ago
8 0

Answer:

If the star has smaller mass than the Sun, it can fuse hydrogen into helium for at least a trillion years. The larger a star, the shorter its life because it fuses hydrogen into helium much more quickly. A star whose mass is more than 20 Suns will run out of hydrogen in only a few hundred million years.

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Technetium 99 releases a gamma ray
GenaCL600 [577]

what?? please reword this

6 0
3 years ago
Which of the following describes the boundaries created by earth's tectonic systems
Dvinal [7]
The earth's plates usually move in three different ways resulting in three different types of plate margins/ boundaries: CONVERGENT, DIVERGENT and TRANSFORM plate boundaries.

When plates move towards each other, they collide and this usually either results in the denser of the plates sliding below the other plate or both plates pushing against each other resulting in both plates being pushed upwards to form often times Fold Mountains.  This type of earth tectonics causes a CONVERGENT (destructive; because the collision of the plates results in loss of earth surface area) plate boundary to be formed.

Plates can also pull away from each other and in so doing creating space usually in the form of a fissure between the two moving plates. This fissure usually also for molten earth (magma) rising to the surface and closing the opening between the plates.  This type of earth tectonic is known to form DIVERGENT (constructive; because it usually results in new land being formed) plate margins.

Plates also slide against each other (side to side) thus not resulting in neither the destruction or creation of new land.  This kind of plate margin is known as the TRANSFORM plate boundary.


The diagram below helps to solidify the points made above.

8 0
3 years ago
You wish to construct a buffer of pH=7.0. Which of the following weak acids (w/ corresponding conjugate base) would you select?
Alex17521 [72]

Answer:

C.) HOCl Ka=3.5x10^-8

Explanation:

In order to a construct a buffer of pH= 7.0 we need to find the pKa values of all the acids given below

we Know that

pKa= -log(Ka)

therefore

A) pKa of  HClO2 = -log(1.2 x 10^-2)

=1.9208

B) similarly PKa of HF= -log(7.2 x 1 0^-4)= 2.7644

C)  pKa of HOCl= -log(3.5 x 1 0^-8)= 7.45

D) pKa of HCN = -log(4 x 1 0^-10)=  9.3979

If we consider the  Henderson- Hasselbalch equation for the calculation of the pH of the buffer solution

The weak acid for making the buffer must have a pKa value near to the desired pH of the weak acid.

So, near to value, pH=7.0. , the only option is HOCl whose pKa value is 7.45.

Hence, HOCl will be chosen for buffer construction.

3 0
3 years ago
Predict the sign of the entropy change, ΔS∘, for each of the reaction displayed.Drag the appropriate items to their respective b
Sonja [21]

Answer:

Ag+(aq)+Br−(aq)→AgBr(s)                                NEGATIVE

CaCO3(s)→CaO(s)+CO2(g)2                           POSITIVE

NH3(g)→N2(g)+3H2(g)                                    POSITIVE

2Na(s)+Cl2(g)→2NaCl(s)                                 NEGATIVE

C3H8(g)+5O2(g)→3CO2(g) +4H2O(g)           POSITIVE

I2(s)→I2(g)                                                        POSITIVE

Explanation:

We have to remember, to solve this problem, that the entropy of a gas is higher than that of a liquid which in turn  is higher than the solid. Therefore, comparing the reactants and products look for changes in the state of reactants and products. We also have to look for the increase or decrease of moles of each state based on the balanced chemical reaction.

Ag+(aq)+Br−(aq)→AgBr(s)

The reaction product is a single solid and the  the reactants were 2 species in solution. The change in entropy is negative.

CaCO3(s)→CaO(s)+CO2(g)2

Here we have a solid reactant and we have a solid product plus a gas product. The change in entropy is positive.

NH3(g)→N2(g)+3H2(g)

We have 4 mole gases as products starting from 1 mol reactant gas, the entropy has increased.

2Na(s)+Cl2(g)→2NaCl(s)

In this reaction 2 mol solid Na and 1 mol Cl₂ gas are converted into 2 mol solid NaCl, the entropy has decreased.

C3H8(g)+5O2(g)→3CO2(g) +4H2O(g)

The products are 7 mol of gas versus 6 mol of gas reactants and therefore entropy has increased.

I2(s)→I2(g)

1 mol solid I₂ goes into 1 mol gas making the change in  the entropy higher.

4 0
3 years ago
Why does mass of popcorn stay the same after popping it
Varvara68 [4.7K]

Answer:

Explanation:

it stays the same because the seeds or whatever in the bag was still the pop corn just not fully devloped

3 0
3 years ago
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