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Rina8888 [55]
2 years ago
14

What do astronomers use to calculate the age of the universe? Check all that apply. dark energy the age of rocks on Earth the ag

e of the oldest stars patterns of background radiation how fast distant galaxies are moving away from us
Chemistry
2 answers:
Hitman42 [59]2 years ago
4 0

The answers are:

The age of the oldest stars

How fast distant galaxies are moving away from us

Patterns of background radiation

Using these techniques, and using the Big Bang as reference point, astronomers estimate that the universe may be approximately 12 billion years old.


Likurg_2 [28]2 years ago
4 0

the age of the oldest stars

patterns of background radiation

how fast distant galaxies are moving away from us

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Help with 5b. Full explanation please
larisa86 [58]
Not elementary school work
8 0
3 years ago
What mass of nitrogen is needed to fill an 855 L tank at STP?
scoundrel [369]

Answer:

It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.

Explanation:

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C or 273.15 °K are used and are reference values for gases.

On the other side, the pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:  

P*V = n*R*T

where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.

So, in this case:

  • P= 1 atm
  • V= 855 L
  • n= ?
  • R= 0.082 \frac{atm*L}{mol*K}
  • T= 273.15 K

Replacing:

1 atm* 855 L= n* 0.082 \frac{atm*L}{mol*K} * 273.15 K

Solving:

n=\frac{1 atm* 855 L}{0.082\frac{atm*L}{mol*K} *273.15 K }

n= 38.17 moles

Being the molar mass of nitrogen N2 equal to 28 g / mol, you can apply the following rule of three: if there are 28 grams in 1 mole, how much mass is there in 38.17 moles?

mass=\frac{38.17 moles*28 grams}{1 mole}

mass= 1,068.76 grams

<u><em> It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.</em></u>

3 0
3 years ago
Coffee is decaffeinated industrially using supercritical (sc) CO2. One advantage to using scCO2 is that the polarity of the supe
koban [17]

Answer:

Yes

Explanation:

A supercritical fluid has good properties for both liquid and as for extraction properties, the advantages then include:

  • The fact that it has a lower viscosity than liquid CO2 allowing it to move through and around coffee beans more thoroughly with creating back pressure
  • Its density is comparable to that of liquid CO2 meaning there is much CO2 per litre as there is liquid form making it more efficient
  • It has a higher diffusivity than liquid CO2 which aids with penetration of the coffee beans on a molecular level

This experiment would not work with tea leaves because they also contain caffeine

6 0
2 years ago
A student has an unknown sample. How can spectroscopy be used to identify the sample?
iogann1982 [59]

Answer: A. It can identify the elements in the sample.

Explanation: on edge

4 0
3 years ago
What would happen to earth's orbit around the sun if there were gravity
kipiarov [429]
If the sun was not there the earth would travel in a straight line
7 0
3 years ago
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