Changes in the total amount of thermal energy provide evidence that chemical reactions have taken place. A chemical reaction in which energy has been absorbed is known as a(n):
Select one:
physical reaction.

endothermic reaction.

reversible reaction.

exothermic reaction.

Answers

Answer 1

Answer:

B. endothermic reaction

Explanation:


Related Questions

2N2 + 502 --> 2N205
Based on the above reaction, if 7 moles of Ny react completely, how many moles of Oz must also react?
ASAP LOOK AT PICTURE

Answers

Answer:

wait are you talking about the bottom question??

If peanut butter wasn't called peanut butter.. what would it be called?

Answers

Answer:

I have no idea

Explanation:

What term is used to define when a substance reacts quickly with oxygen to produce light and heat?

A. rusting
B. sublimation
C. precipitation
D. burning

Answers

Answer:

I think it's a

Explanation:

not sure hssjkskaakakskksskksqoqkakskzksjsj

Answer: The answer is, D) Burning.

Explanation: Some moderator removed my last answer because someone reported it.

The sun is located at 1 astronomical unit from Earth. How far is the next closest star to Earth?

A. It is about twice as far from earth as the sun.
B. It is about 100 times as far from earth as the sun.
C. It is about the same distance from Earth as the
sun.
D. It is many thousands of times as far from the Earth as the sun.

Answers

answer:

d

Explanation:

sun 109 million miles

2 star trillion of miles

Please help I want the answer

Answers

A) Since both are carbons with the only difference in the number of neutrons,

They are called Isotopes

B) Carbon - 12 has 6 protons and 6 neutrons, while Carbon-13 has 6 protons and 7 neutrons,

Therefore Carbon-12 and Carbon-13 have the same number of protons

C) Carbon - 12 has 6 protons and 6 neutrons, while Carbon-13 has 6 protons and 7 neutrons,

Therefore Carbon-12 and Carbon-13 has different numbers of neutrons

D) Sorry i don't know any uses of Carbon-12 and Carbon-13, you might have to research to get it.

E or F) Sodium 23 has 12 neutrons and 11 electrons, because its mass number 23, atomic number is 11 and since protons and electrons count is same, the number of neutrons = mass number - atomic number = 23 - 11 = 12 neutrons

Happy to help :)

If you need any more help, feel free to ask

A student placed a solid in a liquid, which produced the results shown in the following diagram.
solid: 20°C
OOO
gas bubbles
liquid: 20°C
1
2
Which of the following MOST likely took place?
A. a chemical reaction
chemical
o
O B. a phase change
C. a nuclear reaction
D. a destruction of mass

Answers

B.) a phase change. I think but for sure it’s not C-

The most likely to take place when a solid is placed in a liquid at room temperature ( i.e. 20°C ) is ; ( A )  A chemical reaction

Although your question lacks the required diagram a general answer is provided within the scope of your question

When a solid at 20°C is placed inside a liquid also at 20°C  in the laboratory the emergence of gas bubbles shows that there has been a chemical change between the solid and liquid reactant ( i.e. a chemical reaction has taken place ).

Hence we can conclude that what is most likely to have taken place in this situation is a Chemical reaction.

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As Which is a case of drug abuse?

A.

taking an analgesic whenever you have a headache, no matter how mild

B.

taking double the dosage, by accident, of a medicine that your doctor has prescribed

C.

taking a tranquilizer every night when the label warns not to take it on consecutive nightspirin is a widely used drug. What kind of medicine is it?

Answers

Answer :I think it’s c

Hope this helps!
The answer is C. Hope this helps

Elizabeth collects different types of rocks whenever she goes on vacation. She has rocks that contain shiny crystals, grainy rocks, and rocks that are smooth. These rocks are formed? by different processes. Which of the following is NOT a process by which rocks are formed?

A. freezing of sediments.

B. compaction of sediments.

C. heat and pressure within the Earth

D. cooling of magma at Earth's surface​

Answers

Answer:

It should be A. I've never heard of freezing of sediments

PLEASE HELP "Which of the following substances would have the lower concentration of hydrogen ions ?"

Answers

The lower the pH, the greater the concentration of hydrogen ions (this is one of the definitions of an acid: a substance that increases the hydrogen ion concentration in water). So the answer here would be the one denoting the highest pH value, since that would indicate the smallest concentration of hydrogen ions.

That would be the substance with a pH of 11.2. Thus, the second answer choice here would be correct.

Calculate the pH of the solutions with the following [OH-].

Answers

(2,4)distance graph

6.
Why are estuaries home to diverse marine life not found elsewhere?
is hrimming with

Answers

Answer:

Estuaries are bodies of water where rivers meet the sea or a large lake. Rivers spread out and slow when they meet the sea, creating unique conditions that are not found elsewhere. They provide homes for diverse wildlife, including popular fish species.

What is the energy change per gram of ice when an iceberg composed of pure water, cp = 2.06 J/(g·K), is heated from 25°C to 15°C?

A. 21 J
B. 0.21 J
C. 210 J
D. It is impossible to calculate without knowing the mass of the iceberg

Answers

Answer:

A. 21 J

Explanation:

Your temperature change is 10 degrees Celsius, or 10 Kelvin, it makes no difference either way.

Cp = 2.06 J/g•K

Multiply by the temperature change to just get J/g

2.06 J/g•K • 10 K = 20.6 J/g ≈ 21 J/g

21 J is the energy change per gram of ice when an iceberg composed of pure water, cp = 2.06 J/(g·K) which is heated from 25°C to 15°C. So, the correct option is A.

What is Heat?

Heat is defined as the energy that is transferred from one body to another as a result of a difference in temperature, when two bodies at different temperatures are brought together, the energy transferred is that of the hotter body which flows towards the colder body.

In this case, according to the equation for the calculation of the heat during a heating process

[tex]Q= mC (T_f- T_i)[/tex]

It is possible to calculate mass per gram of ice by dividing both sides by removing m from the equation, we plug in the given specific heat and final and initial temperatures to get:

[tex]Q= 2.06 \frac{J}{g degree C} [-15 Degree C- (-25 Degree C][/tex]

[tex]Q= 20.6\frac{J}{g}[/tex] which is equals to 21° C

21 J is the energy change per gram of ice when an iceberg composed of pure water, cp = 2.06 J/(g·K) which is heated from 25°C to 15°C.

Therefore, the correct option is A.

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How are plant cells different from animal cells?

Select the three correct statements.

A. Their cells have cell walls.
B. They can convert the sun's energy into food.
C. They have chloroplasts.
D. They can move around.
E. They cannot make their own food.

pls help this is due today

Answers

Answer:

b.

They can convert the sun's energy into food.

Answer:

its letter A

because Plant cells have a cell wall, but animals cells do not.

7
Why might living in a high-pollution area have a negative effect on a person's
thyroid?
I

Answers

Answer: since the thyroid produces hormones, the chemicals made by our bodies. Living where there is a lot of pollution would expose a person to many other chemicals -- gas fumes, contaminants in food and water, and so on. I hope this helped!!

Hydrogen and Oxygen combine to form water. In this chemical reaction, who represents the reactions(s)

A. water
B. oxygen and water
C.hydrogen and water
D. hydrogen and oxygen

Answers

I think it is D but I’m not sure

Which of the following is an example of a micro-habitat?

a
Abuela's vegetable garden on her huge farm
b
Ms. Steinmann's 200 gallon fish tank
c
woods behind the school
d
the algae growing on a seashell where tiny sea animals called plankton live

Answers

I believe it is d, a microhabitat is a small area which differs somehow from the surrounding habitat. Its unique conditions may be home to unique species that may not be found in the larger region.

After a skydiver deploys
his parachute, his rate of
speed decreases.

Answers

Answer:

As a skydiver falls, he accelerates downwards, gaining speed with each second. The increase in speed is accompanied by an increase in air resistance (as observed in the animation below). This force of air resistance counters the force of gravity. As the skydiver falls faster and faster, the amount of air resistance increases more and more until it approaches the magnitude of the force of gravity. Once the force of air resistance is as large as the force of gravity, a balance of forces is attained and the skydiver no longer accelerates. The skydiver is said to have reached a terminal velocity.

What color is an orange?

Answers

Answer:

orange

Explanation:

As part of each science lab, Mr. Arico requires his student to wash their glassware, so it is clean for the next class. He has found that the glassware is cleaner when students wash it in front of their classmates. This is best explained by

social facilitation
deindividuation
social loafing
the mere exposure effect
groupthink

Answers

Answer:

social facilitation

Explanation:

The glassware is cleaner when students wash it in front of their classmates is best explained by social facilitation. Hence, option A is correct.

What is social facilitation?

Social facilitation is a psychological concept relating to the tendency for the presence of others to improve a person's performance on a task.

Social Loafing: When a person does not show much effort to achieve a goal when they work in a group than when they work alone.

Social Facilitation: When a person can do better at simple tasks when in the presence of other people.

So the first one is basically saying a person is less working when n a group of other and the second one is saying that this person can work on simple things when people are around.

Hence, the glassware is cleaner when students wash it in front of their classmates is best explained by social facilitation.

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What volume of 5.00 M KI stock solution is needed to make 250. mL of a 1.50 M solution?
A) 0.0300 mL
B) 33.3 mL
C) 75.0 mL
D) 833 mL

Answers

So it says 5.00 M KL so we use that number and now we have 250 mL so if we use those to number and the 1.50 we get C

Taking into account the definition of dilution, the correct answer is option C): 75 mL of the stock solution are required to prepare 250 mL of a 1.50 M solution.

Definition of dilution

You have to know that when it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where:

Ci: initial concentrationVi: initial volumeCf: final concentrationVf: final volume

Volume of 5.00 M KI stock solution needed

In this case, you know:

Ci= 5 M Vi= ?Cf= 1.5 MVf= 250 mL= 0.250 L (beign 1 L= 1000 mL)

Replacing in the definition of dilution:

5 M× Vi= 1.5 M× 0.250 L

Solving:

Vi= (1.5 M× 0.250 L)× 5 M

Vi= 0.075 L= 75 mL

In summary, the correct answer is option C): 75 mL of the stock solution are required to prepare 250 mL of a 1.50 M solution.

Learn more about dilution:

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As the randomness of a system increases, the entropy of the system:

A) decreases
B) increases
C) remains the same

Answers

Answer:

it most likely increases

Covert 50oC to k
(I’ll mark you as brainlister)

Answers

Answer:

323 K

Explanation:

To convert Celcius to kelvin first you need to remember this equation:

C + 273 = K (K = kelvin and C = celsius)

Next, you substitute with what you have given:

50 + 273 = K

Solve the equation by adding 50 and 273

k = 323


State TWO ways in which stress could impact negatively on student's
performance at College or university.​

Answers

Two ways that stress could negatively impact a students performance is by causing them to procrastinate. When you're stressed, you tend to keep putting things off because you "just can't deal with it" at the moment. This could cause the student to turn in their assignments late (or not at all) and cause their grades to drop. Additionally, when you're stressed, it's harder to fall asleep, and once you are, you don't sleep as well. Sleep deprivation can greatly affect a student's in class performance by causing them to fall asleep in class, or not pay attention as well.

Perform the following
mathematical operation, and
report the answer to the correct
number of significant figures.
3.47 x 6.7 = [?]

Answers

Answer:

[tex]3.4 \times 6.7 = 23.249[/tex]

Answer:

23.25

Explanation:

3.47x6.7= 23.249= 23.25 / 23.

Given 2Na + Cl2=2NaCl, what is the excess reactant? What is the limiting reactant?

Answers

Answer: The limiting reactant is Na

Explanation:

Which of the following arrangements of electrons represent Potassium? *

a. 2,6,3,8

b. 2,7,8,2

c. 2,8,8,1

d. 2,9,7,1​

Answers

C. 2,8,8,1 also know as K on the periodic table

Hydrogen bonding in water molecules results in all of the following properties except?

Answers

Answer:

Transparent Color

Explanation:

Hydrogen bonds here in water provides a lot of benefits which includes cohesion, releasing heat when forming, Also because of the fact that water molecules are polar, they form hydrogen molecules and give water some characteristics which ranges from high boiling point, relative gravity, adhesion ad also cohesion. It is also known that oxygen atom attracts the electrons more strongly than the hydrogen.

   A transparent colour falls in no place and do not really have any correlation in oxygen and hydrogen relationship.

The presence of hydrogen bonds in molecules affects the bulk properties of the molecules.

Though the question is incomplete but I will try to help you the much I can. hydrogen bonding is said to occur in molecules where hydrogen is bonded to a highly electronegative atom such as nitrogen, oxygen and fluorine.

The presence of hydrogen bonding in molecules affects its bulk properties such as melting and boiling points, density and surface tension.

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help me i mark brain thing

Answers

Answer:

Becuase they can go through mountains and hills, they curve of of those.

Calculate the standard potential, ∘, for this reaction from its equilibrium constant at 298 K. X(s)+Y3+(aq)↽−−⇀X3+(aq)+Y(s)=6.90×10−8 X ( s ) + Y 3 + ( aq ) ↽ − − ⇀ X 3 + ( aq ) + Y ( s ) K = 6.90 × 10 − 8

Answers

Answer: The standard potential is  -0.141 V

Explanation:

To calculate the Gibbs free energy for given value of equilibrium constant we use the relation:

[tex]\Delta G=-RTlnK[/tex]

where,

= standard Gibbs free energy = ?

R = Gas constant = 8.314 J/Kmol

T = temperature = 298 K

K = equilibrium constant =

Putting values in above equation, we get:

[tex]\Delta G=40853J[/tex]

Also [tex]\Delta G=-nFE^0[/tex]

where n = no of electrons gained or lost = 3

F = Faradays constant = 96500 C

[tex]E^0[/tex] = standard potential = ?

[tex]40853=3\times 96500\times E^0[/tex]

[tex]E^0=-0.141V[/tex]

Thus the standard potential is -0.141 V

HELPP asap I’ll mark you as brainlister!!!!!!

Answers

3.50 atm

Total pressure is just the sum of partial pressures. If you have 2.07 atm of pressure in the cylinder and then add 1.43 atm, you just add the two pressure together to get the total.
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