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givi [52]
3 years ago
7

Which of the following is most likely an indication of a chemical change?

Chemistry
1 answer:
mamaluj [8]3 years ago
5 0

Hello there!

Question: Which of the following is most likely an indication of a chemical change?

Answer Choices:

A. A loud sound when an MP3 player is turned on.

B. A loud sound when someone claps their hands.

C. A loud sound when a starter's pistol is fired at a race.

D. A loud sound when a large object falls to the ground.

Correct Answer:

C. A loud sound when a starter's pistol is fired at a race.

Reasons:

A would not be correct since an MP3 player is a mechanical object and does not mix any substances that create a reaction.

B would not be correct since clapping hands causes a loud sound due to two forces slamming together and causes a disturbance in the air.

D would not be correct since a large object falling to the ground does not indicate any chemical reactions or changes since its merely the result of a mass hitting another mass.

C would be correct since the gunpowder mixes with other substances inside the pistol's chamber and causes and explosion, and explosions are part of a chemical reaction indicators.

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During the first half of the 20th century, the theory of plate tectonics was developed. Evidence supporting this theory included
Makovka662 [10]

A) GPS monitoring and satellite imagery of crustal movements

Explanation:

The most recent evidence supporting the theory of plate tectonics is the use of  GPS monitoring and satellite imagery of crustal movements.

GPS denotes Global Positioning Systems.

Satellite imagery is a recent advancement in the study of moving plates.

  • The global positioning system uses the position of a system of satellites in space to delineate positions on earth.
  • It works on the principles of triangulation and this helps to fix positions of objects on the earth surface.
  • With this, the change in position of the plates can be recorded by known fixed positions of objects.
  • Satellite imagery helps to map changes in terrain with time.
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5 0
3 years ago
HELP PLEASE I BEG OF YOU
Vitek1552 [10]

Answer:

37.7%

Explanation:

58% of 65 is 37.7%

7 0
2 years ago
Two crates, one heavy and one light, are at rest on a waxed floor. Which crate will need the greater force to give the same chan
otez555 [7]
The heavy one because mass times force is equal to speed. The lighter one has less mass to it goes faster without as much effort. I hope that helps!
4 0
3 years ago
Read 2 more answers
How is primary selection different from secondary succession?
PIT_PIT [208]

Answer:

Explanation:

Primary and secondary succession occur after both human and natural events that cause drastic change in the makeup of an area. Primary succession occurs in areas where there is no soil and secondary succession occurs in areas where there is soil.

In primary succession, newly exposed or newly formed rock is colonized by living things for the first time. In secondary succession, an area previously occupied by living things is disturbed—disrupted—then recolonized following the disturbance.

Hope this helped :)

-<em>Akito</em>

8 0
2 years ago
• We obtained the above 10.00-mL solution by diluting a stock solution using a 1.00-mL aliquot and placing it into a 25.00-mL vo
garik1379 [7]

Answer:

a) The relationship at equivalence is that 1 mole of phosphoric acid will need three moles of sodium hydroxide.

b) 0.0035 mole

c)  0.166 M

Explanation:

Phosphoric acid is tripotic because it has 3 acidic hydrogen atom surrounding it.

The equation of the reaction is expressed as:

H_3PO_4 \ + \ 3NaOH -----> Na_3 PO_4 \ + \ 3H_2O

1 mole         3 mole

The relationship at equivalence is that 1 mole of phosphoric acid will need three moles of sodium hydroxide.

b)  if 10.00 mL of a phosphoric acid solution required the addition of 17.50 mL of a 0.200 M NaOH(aq) to reach the endpoint; Then the molarity of the solution is calculated as follows

H_3PO_4 \ + \ 3NaOH -----> Na_3 PO_4 \ + \ 3H_2O

10 ml            17.50 ml

(x) M              0.200 M

Molarity = \frac{0.2*17.5}{1000}

= 0.0035 mole

c) What was the molar concentration of phosphoric acid in the original stock solution?

By stoichiometry, converting moles of NaOH to H₃PO₄; we have

= 0.0035 \ mole \ of NaOH* \frac{1 mole of H_3PO_4}{3 \ mole \ of \ NaOH}

= 0.00166 mole of H₃PO₄

Using the molarity equation to determine the molar concentration of phosphoric acid in the original stock solution; we have:

Molar Concentration =  \frac{mole \ \ of \ soulte }{ Volume \ of \ solution }

Molar Concentration = \frac{0.00166 \ mole \ of \  H_3PO_4 }{10}*1000

Molar Concentration = 0.166 M

∴  the molar concentration of phosphoric acid in the original stock solution = 0.166 M

6 0
3 years ago
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