All categories

2 years ago

describe how astronomers are able to use the light from a distant star to determine what elements make up the stars.

Chemistry

1 answer:

dlinn [17]2 years ago

7 0

Answer:

The spectra of the Sun and stars exhibited bright and dark lines called Fraunhofer lines. These were shown to be caused by elements emitting or absorbing light at specific wavelengths. Because each element emits or absorbs light only at specific wavelengths, the chemical composition of stars can be determined.

You might be interested in

The half life of radon-222 is 3.8 days. How Much of a 100g sample is left after 15.2 days

professor190 [17]

Answer:

6.2 g

Explanation:

In a first-order decay, the formula for the amount remaining after n half-lives is

$N = \frac{N_{0}}{2^{n}}$

where

N₀ and N are the initial and final amounts of the substance

1. Calculate the number of half-lives.

If $t_{\frac{1}{2}} = \text{3.8 da}$

$n = \frac{t}{t_{\frac{1}{2}}} = \frac{\text{15.2 da}}{\text{3.8 da}}= \text{4.0}$

2. Calculate the final mass of the substance.

$\text{N} = \frac{\text{100 g}}{2^{4.0}} = \frac{\text{100 g}}{16} = \text{6.2 g}$

4 0

2 years ago

Help me with this question?!!

olya-2409 [2.1K]

Answer:

500 mL

Explanation:

Step 1: Find conversions

1 mL = 0.0338 oz

Step 2: Use Dimensional Analysis

$16.9 \hspace{2} oz(\frac{1 \hspace{2} mL}{0.0338 \hspace{2} oz} )$ = 500 mL

3 0

2 years ago

How many grams of material is lost in the aqueous phase if two extractions are carried out on 100 mL of a 5% (m/v) aqueous solut

san4es73 [151]

Answer:

4.94g of material

Explanation:

Partition coefficient (Kp) of a substance is defined as the ratio between concentration of organic solution and aqueous solution, that is:

Kp = 8 = Concentration in Ethyl acetate / Concentration in water

100mL of a 5% solution contains 5g of material in 100mL of water. Thus:

8 = X / 100mL / (5g-X) / 100mL

Where X is the amount of material in grams that comes to the organic phase.

8 = X / 100mL / (5g-X) / 100mL

8 = 100X / (500-100X)

4000 - 800X = 100X

4000 = 900X

4.44g = X

Thus, in the first extraction you will lost 4.44g of material from the aqueous phase.

And will remain 5g-4.44g = 0.56g.

In the second extraction:

8 = X / 100mL / (0.56g-X) / 100mL

8 = 100X / (56-100X)

448 - 800X = 100X

448 = 900X

0.50g = X

In the second extraction, you will extract 0.50g of material

Thus, after the two extraction you will lost:

4.44g + 0.50g = 4.94g of material

6 0

2 years ago

Which of the following describes an endothermic reaction?

Alenkinab [10]

The endothermic reaction would be D. Batter becomes a pancake when heated. This is because the batter is absorbing the heat in order to turn into a pancake.

Answer is D. Batter becomes a pancake when heated.

Please vote brainliest thank you!

4 0

2 years ago

Is material that has a density of 0.2g/ml good for building a bridge or for making couch cushions

lisov135 [29]

D = 0.2 g / ml = 0.2 g / cm³
For example, density of steel is 7.85 g / cm³.
Density of pure water is 1.0 g/cm³. An object which has a density < 1.0 g/cm³ will float in water.
Answer: Material that has a density of 0.2 g/ml ( 0.2 g/cm³ ) is good for making couch cushions.

8 0

3 years ago

Read 2 more answers