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kotykmax [81]
3 years ago
5

20. Which of the following are pure substances?

Chemistry
1 answer:
Juliette [100K]3 years ago
3 0
The answer is III and V
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Water freezes at 0∘C and CO freezes at −205∘C. Which type of intermolecular force accounts for this difference in freezing point
Assoli18 [71]

Explanation:

The dipoles in CO are in opposite directions so they cancel each other out, although CO₂ has polar bonds, it is a nonpolar molecule. Therefore, the only intermolecular forces are London dispersion forces. Water (H2O) has hydrogen bond present which is a polar bond which has a high intermolecular force.

Water which has high intermolecular force will require more energy that is a higher temperature to overcome these attractions and are pulled together tightly to form a solid at higher temperatures, so their freezing point is higher.

As the temperature of a liquid decreases, the average kinetic energy of the molecules decreases and they move more slowly.

CO with lower intermolecular forces will not solidify until the temperature is lowered further.

6 0
3 years ago
How does a concave lens differ from a convex lens? A) A convex lens is another way to describe a plane mirror; a concave lens is
elixir [45]
<h3><u>Answer;</u></h3>

C) A convex lens has a thick center and thin edges; a concave lens has a thin center and thicker edges.

<h3><u>Explanation;</u></h3>
  • Convex lens refers to the lens which merges the light rays at a particular point, that travels through it, while a concave lens can be identified as the lens which disperses the light rays around, that hits the lenses.
  • A convex lens is thicker at the center, as compared to its edges, while a concave lens is thinner at the center as compared to its edges.
  • A concave lens is thicker at the edges than in the middle and spreads light rays apart producing an image smaller than the actual object. A convex lens on the other hand, is thinner at the edges and thicker towards the center, that is they are bent towards a central point.
7 0
2 years ago
Read 2 more answers
Which of the following elements can form diatomic molecules held together by triple covalent bonds?
Art [367]
Nitrogen can form a diatomic molecule held together by triple bonds.
6 0
2 years ago
Read 2 more answers
Convert 5.4g of NaCl to moles
sammy [17]

Answer:

.0924 moles of NaCl

Explanation:

So you know you have 5.4 g of NaCl and you need to know how many moles there are in this amount of NaCl

  1. You'll need to find the atomic mass of the compound NaCl to help you solve for moles
  • Sodium (Na) on the periodic table has a mass of 22.99
  • Chlorine (Cl) on the periodic table has a mass of 35.45

Add these two together----> 22.99 + 35.45 = 58.44

Now you can calculate for moles

<u>Written-out method:</u>

<u>5.4 grams of NaCl  |   1 mole of  NaCl              </u>

                                | 58.44 grams NaCl                = .0924 moles of NaCl

<u>Plug into calculator method:</u>

(5.4 g of NaCl/ 58.44g NaCl= .0925 moles)

7 0
2 years ago
A sample of nitrogen gas is collected over water at temperature of 20.0˚C. What is the pressure of the nitrogen gas if atmospher
Levart [38]

Answer:

P_N=0.987atm

Explanation:

Hello there!

In this case, for these problems about collecting a gas over water, we must keep in mind that once the gas has been collected, the total pressure of the system is given by the atmospheric pressure, in this case 1.01 atm. Next, since we also have water in the mixture, we can write the following equation:

P_T=P_w+P_N

Thus, by solving for the pressure of nitrogen and using consistent units, we obtain:

1.01atm=17.5torr*\frac{1atm}{760torr} +P_N\\\\P_N=1.01atm-0.023atm\\\\P_N=0.987atm

4 0
3 years ago
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