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Ostrovityanka [42]
3 years ago
7

What is the second most abundant element in stars? A. helium B. iron C. hydrogen D. oxygen

Chemistry
1 answer:
devlian [24]3 years ago
8 0
<span>The </span>abundance of a chemical element<span> is a measure of the </span>occurrence<span> of the </span>element<span> relative to all other elements in a given environment. Abundance is measured in one of three ways: by the </span>mass-fraction<span> (the same as weight fraction); by the </span>mole-fraction<span> (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the </span>volume-fraction<span>. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and </span>ideal gas<span> mixtures. Most abundance values in this article are given as mass-fractions.

</span>
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Which molecule has a polar bone, but is no polar in nature?
aliya0001 [1]

Carbon Dioxide has two polar C=O. bonds, but the geometry of Carbon dioxide is linear so that the two bond dipole moments cancel and there is no net molecular dipole moment; the molecule is nonpolar.

I hope this helps :)

6 0
3 years ago
What mass of dinitrogen monoxide, N2O, contains the same number of molecules as 3.00 g of trichlorofluoromethane, CCl3F?
erica [24]

Answer:

0.9612 g

Explanation:

First we <u>calculate how many moles are there in 3.00 g of CCl₃F</u>, using its <em>molar mass</em>:

  • 3.00 g CCl₃F ÷ 137.37 g/mol = 0.0218 mol CCl₃F

Now, we need to calculate how many grams of N₂O would have that same number of molecules, or in other words, <em>the same amount of moles</em>.

Thus we <u>calculate how many grams would 0.0218 moles of N₂O weigh</u>, using the <em>molar mass of N₂O</em> :

  • 0.0218 mol N₂O * 44.013 g/mol = 0.9612 g N₂O
3 0
3 years ago
Traveling at the speed of light - how long would it take, in years, to reach the top of the pile of balls? Show all calculations
marusya05 [52]

The time taken for the object to reach to top of pile is 0.012 year.

<h3>Time of motion </h3>

The time taken for the object to reach to top of pile is calculated as follows;

time of motion = distance traveled/speed

time of motion = (1.1 x 10¹⁴ x 10³ m)/(3 x 10⁸ m/s)

where;

  • speed of light = 3 x 10⁸ m/s

time of motion = 3.67 x 10⁵ sec = 0.012 year

Thus, the time taken for the object to reach to top of pile is 0.012 year.

Learn more about time of motion here: brainly.com/question/2364404

#SPJ1

7 0
2 years ago
5g of a mixture of KOH and KCl with water form a solution of 250mL. We have 25ml of this solution and we mix it with 14,3mL of H
cricket20 [7]
We know that the number of moles HCl in 14.3mL of 0.1M HCl can be found by multiplying the volume (in L) by the concentration (in M).
(0.0143L HCl)x(0.1M HCl)=0.00143 moles HCl

Since HCl reacts with KOH in a one to one molar ratio (KOH+HCl⇒H₂O+KCl), the number of moles HCl used to neutralize KOH is the number of moles KOH. Therefore the 25mL solution had to contain 0.00143mol KOH.

To find the mass of KOH in the original mixture you have to divide the number of moles of KOH by the 0.025L to find the molarity of the KOH solution..
(0.00143mol KOH)/(0.025L)=0.0572M KOH

Since the morality does not change when you take some of the solution away, we know that the 250mL solution also had a molarity of 0.0572.  That being said you can find the number of moles the mixture had by multiplying 0.0572M KOH by 0.250L to get the number of moles of KOH.
(0.0572M KOH)x(0.250L)=0.0143mol KOH

Now you can find the mass of the KOH by multiplying it by its molar mass of 56.1g/mol.
0.0143molx56.1g/mol=0.802g KOH

Finally you can calulate the percent KOH of the original mixture by dividing the mass of the KOH by 5g.
0.802g/5g=0.1604
the original mixture was 16% KOH

I hope this helps.

7 0
3 years ago
What is the composition of 'Clean dry air'<br><br> - Idk what subject its just science
Luba_88 [7]
Dry air is a mixture of nitrogen, oxygen, carbon dioxide etc.
air is a mixture of gases 78% nitrogen an 21% oxygen and other components.
7 0
3 years ago
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