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Citrus2011 [14]
3 years ago
6

A teacher is demonstrating physical and chemical changes to her class. Which action should they use to demonstrate a chemical ch

ange?. Single choice.
(5 Points)

Cutting a piece of paper with scissors.

Ripping a piece of paper with their hands.

Burning a piece of paper with a match.

Folding a piece of paper into an airplane.
Chemistry
1 answer:
olya-2409 [2.1K]3 years ago
5 0
Burning a piece of paper with a match.



Explanation:

A chemical change is something that changes the actual make up of an object. It happens at a chemical level and can only sometimes be observable. For example cutting a paper or folding it is not changing the makeup of the paper, just the shape.
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The coolant in automobiles is often a 50/50 % by volume mixture of ethylene glycol, C2H6O2, and water. At 20°C, the density of e
Misha Larkins [42]

Explanation:

Let the volume of the solution be 100 ml.

As the volume of glycol = 50 = volume of water

Hence, the number of moles of glycol = \frac{mass}{molar mass}

                                                  = \frac{density \times volume}{molar mass}

                         = \frac{1.1088 \times 50}{62 g/mol}

                         = 0.894 mol

Hence, number of moles of water = \frac{50 \times 0.998}{18}

                                             = 2.77

As glycol is dissolved in water.

So, the molality = 0.894 \times \frac{1000}{49.92}

                           = 17.9

Therefore, the expected freezing point = -1.86 \times 17.9

                                                                  = -33.31^{o}C

Thus, we can conclude that the expected freezing point is -33.31^{o}C.

6 0
3 years ago
10. When the pressure on a gas inetcases three times, by how much will the volume incrcase or decrease?
blagie [28]

Answer:The answer to this question comes from experiments done by the scientist Robert Boyle in an effort to improve air pumps. In the 1600's, Boyle measured the volumes of gases at different pressures. Boyle found that when the pressure of gas at a constant temperature is increased, the volume of the gas decreases. when the pressure of gas is decreased, the volume increases. this relationship between pressure and volume is called Boyle's law.

Explanation: So, at constant temperature, the answer to your answer is: the volume decreases in the same ratio as the ratio of pressure increases.

BUT, in general, there is not a single answer to your question. It depend by the context.

For example, if you put the gas in a rigid steel tank (volume is constant), you can heat the gas, so provoking a pressure increase. But you won't get any change in volume.

Or, if you heat the gas in a partially elastic vessel (as a tire or a soccer ball) you will get both an increase of volume AND an increase of pressure.

FINALLY if you inflate a bubblegum ball, the volume will be increased without any change in pressure and temperature, because you have increased the NUMBER of molecules in the balloon.

There are many other ways to change volume and pressure of a gas that are different from the Boyle experiment.

4 0
3 years ago
Please help<br>What is the possible ions of vanadium?
svetlana [45]

V+5, V+4, V+3, and V+2

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2 years ago
The average strength of a hydrogen bond is approximately what percent of the average strength of a covalent bond?
lozanna [386]

<span>Hydrogen bonds are approximately 5% of the bond strength of covalent bonds, for example (C-C or C-H bonds).
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20 kJ/350 kJ = 0,057 = 5,7 %.</span>

8 0
3 years ago
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