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stira [4]
3 years ago
7

Are blue stars young or old? How can you tell?.

Chemistry
1 answer:
andriy [413]3 years ago
4 0
Astronomers measure the brightness of stars using light-years. This means that the light we see now left in that years ago, traveling through space in that distance at kilometer per second.

A star is born, it radiates energy for a long time, toward the end it expands, it may or may not explode, and then it dies. It vary in sizes, masses and surface temperature range. The colors of stars reflect their surface temperature. Their relative brightness is expressed in a scale of six magnitudes. The brightest the stars are first-magnitude stars, while the dimmest are sixth-magnitude stars.
 
The lower the number, the brighter the star.

For example:
                      Star color                        Surface Temperature
                     Blue-white                         around 25 000 K & higher
                     white                                  around 10 000 K
                     yellow                                around 7 000 K
                     Red                                    around 5 000 K & lower

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What is missing from the solubility graph shown on the right? A graph with temperature in degrees Celsius ranging from 0 to 100
AVprozaik [17]

Answer:

graph title, label for the y axis, and legend explaining the orange and blue colors

Explanation:

8 0
2 years ago
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Delvig [45]
Here are the answers. A,A,A,C,A,C. 

I hope this helps!
4 0
3 years ago
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What is the pH of this solution?
Vesnalui [34]

Answer:

pH = 11.216.

Explanation:

Hello there!

In this case, according to the ionization of ammonia in aqueous solution:

NH_3+H_2O\rightleftharpoons NH_4^++OH^-

We can set up its equilibrium expression in terms of x as the reaction extent equal to the concentration of each product at equilibrium:

Kb=\frac{[NH_4^+][OH^-]}{[NH_3]} \\\\1.80x10^{-5}=\frac{x*x}{0.150-x}

However, since Kb<<<1 we can neglect the x on bottom and easily compute it via:

1.80x10^{-5}=\frac{x*x}{0.150}\\\\x=\sqrt{1.80x10^{-5}*0.150}=1.643x10^{-3}M

Which is also:

[OH^-]=1.643x10^{-3}M

Thereafter we can compute the pOH first:

pOH=-log(1.643x10^{-3}M)\\\\pOH=2.784

Finally, the pH turns out:

pH=14-2.784\\\\pH=11.216

Regards!

5 0
3 years ago
Is using gasoline to drive a chemical or physical
Flauer [41]

Answer:

Explanation:

Driving a car (burning gas is a chemical change) and almost all the plastics we use are made by chemical reactions of different components.

3 0
3 years ago
Which process is exothermic?
valkas [14]
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Therefore, the answer is B. MELTING OF COPPER
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3 years ago
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