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Alika [10]
3 years ago
8

Which of the following is a physical change?

Chemistry
2 answers:
vodka [1.7K]3 years ago
6 0
Hello,
A physical change describes a change that does physically and does not display “chemical” signs which are signs that indicate a precipitate being formed, change in color, density, or producing gas, etc. “Tearing a piece of paper in half” is a physical change because like I said earlier it doesn’t show any chemical change signs. I hope this helps you out!
OLga [1]3 years ago
6 0

Answer:

Tearing a piece of paper in half is a physical change.

Explanation:

A physical change is a change in which the molecular composition of the subject does not change. Since tearing a paper in half does not cause a change in the molecules of the paper, it is a physical change.

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If you have a chemical reaction and there are 36 grams of reactant. How much product are you going to have to have?
kolezko [41]

Answer:

36

Explanation:

products and reactants have to be equal

7 0
3 years ago
If 7.4 moles of carbon dioxide is produced in this reaction, how many moles of oxygen gas would be needed?
Nimfa-mama [501]

Answer:

11.6 mol O₂

Explanation:

  • C₇H₁₆ + 11 O₂ → 7 CO₂ + 8 H₂O

In order to solve this problem we need to <u>convert moles of carbon dioxide (CO₂) into moles of oxygen gas (O₂)</u>. To do so we'll use a conversion factor containing the <em>stoichiometric coefficients</em> of the balanced reaction:

  • 7.4 mol CO₂ * \frac{11molO_2}{7molCO_2} = 11.6 mol O₂
4 0
3 years ago
Espresso Coffee House is designing a coffee mug that keeps liquids hot. The research department tested several different materia
raketka [301]

Answer:

This question is incomplete

Explanation:

This question is incomplete because the result of the described experiment would have better determined the type of scientific explanation to profer. However, the type of material that will preserve the relative hotness or temperature of the hot coffee for the longest time will be a material than can resist heat transfer. These materials tend to keep hot substances hot by not allowing the heat of the coffee to be conducted or pass through it. These materials are mostly insulators or made by placing an insulator between two heat conductors.

Generally, heat is usually transferred from a region of higher concentration to a region of lower concentration, hence when the heat is denied of this transfer, the heat will remain trapped in the "heat-donor" substance (in this case the hot coffee). Thus, the material chosen (A, B or C) will be the material that resists heat transfer the most based on the explanation above.

4 0
3 years ago
What is the frequency of a wave that has 3 waves every five seconds?
Dmitry [639]

Answer:

Frequency, f = 0.6 Hz

Explanation:

We have,

Number of waves passing through a point are 3

Time for which the waves are passing is 5 seconds

It is required to find the frequency of a wave. The frequency of a wave is defined as the no of waves per unit time. So,

f=\dfrac{n}{t}\\\\f=\dfrac{3}{5}\\\\f=0.6\ Hz

So, the frequency of a wave is 0.6 Hz.

7 0
3 years ago
A bacteria culture begins with 15 bacteria which double in amount at the end of every hour. Solve for the number of bacteria tha
pshichka [43]
The number of bacteria is given by:
N(t) = N(o) x 2ⁿ
Where N(t) is the number after n hours have passed and N(o) is the original number which is 15.
The number grown in the 12th hour is the difference in the number after the 11th and the 12th hour. Thus:
15 x 2¹² - 15 x 2¹¹
= 30,720 bacteria
5 0
3 years ago
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