A machine used 20 J of energy to make a
bicycle start. However, 6 J of energy was
wasted as heat. What is the percentage
efficiency of the machine?
a 30%
b 75%
C 70%
d 60%​

Answers

Answer 1

Answer:

a. 30%

Explanation:

Given the following data;

Energy as effort, Ee = 20 J

Energy as heat, Eh = 6 J

To find the percentage efficiency (P.E);

P.E = Eh/Ee * 100

Substituting into the formula, we have;

P.E = 6/20 * 100

P.E = 6 * 5

P.E = 30 %

Therefore, the percentage efficiency of the machine is 30 %.


Related Questions

Un movil avanza a 20 m/s y recorre una distancia de 800 km. Determinar el tiempo en horas que utiliza

Answers

Answer:

t = 11.1 hours

Explanation:

The question says that, "A mobile advances at 20 m / s and travels a distance of 800 km. Determine the time in hours you use".

Given that,

Speed of a mobile, v = 20 m/s = 72 km/h

Distance, d = 800 km

We know that,

Speed = distance/time

So,

[tex]t=\dfrac{d}{v}\\\\t=\dfrac{800}{72}\\\\t=11.1\ h[/tex]

So, it will take 11.1 hours.

This Is Science , please help it’s due at 3 , but I dont mind if its a little late.

Answers

Answer:

uhm you can get all these answers from go ogle but just so you dot get in trouble click the tree dots at the top right of your screen (this is if your using crome) and go to history click the square and there should be a delete thing

Explanation:

Answer:

4. I and II   9. tornado

Explanation:

A 1200 kg car accelerats from reat to 10.0 m/s in a time of 4.50 seconds. Calculate the force that thr car's tires exerted on the road.​

Answers

Answer:

2667 N

Explanation:

Method 1: Impulse

We can solve this problem by using the impulse formula.

FΔt = mΔv  Δt = time interval, m = mass of the car (kg), Δv = change in velocity

We have three known variables, so we can solve for the fourth: F.

Divide Δt from both sides to isolate F.

F = (mΔv)/Δt  

Substitute known values into the equation.

F = [(1200 kg)(10 m/s -  0 m/s)] / 4.5 s F = [(1200)(10)]/4.5 F = 12000/4.5 F = 2666.666667 N

The force that the car's tires exert on the road is 2667 N.

Method 2: Newton's Second Law

The force that the car's tires exert on the road is equivalent to the force that the road exerts on the car due to Newton's Third Law of Motion.

We can calculate the force that the car's tires exert on the road by using the formula F = ma, which was derived from Newton's Second Law of Motion.

F = ma F = force exerted on the car, m = mass of the car (kg), a = acceleration of the car (m/s²)

We are given the mass of the car, velocity of the car, and the time in which it accelerated.

We can use this equation for acceleration:

a = Δv/Δt Δv = final velocity - initial velocity (change in velocity), Δt = time interval

The car started from rest, meaning it had an initial velocity of 0 m/s. Its final velocity was 10 m/s. The time that it took for the car to go from 0 m/s to 10 m/s was 4.5 seconds.

a = (10 m/s - 0 m/s) / 4.50 s a = 10/4.5 a = 2.222... m/s²

Now we have two known variables, mass and acceleration. We can solve for the force exerted on the car (and thus, the force the car exerts on the road) using the formula F = ma.

F = ma F = (1200 kg)(2.222... m/s²) F = 1200 · 2.222...F = 2666.666667 N

The force that the car's tires exert on the road is 2667 N.

The three things to remember about gravitational forces in space are: 1. 2. 3.

Answers

Answer:

(1) The gravitational forces are inversely proportional to the square of the distance between the objects. More is the distance between the objects , less will be the gravitational force between them.

(2) The gravitational forces are the weakest of all the four fundamental forces (Nuclear forces, weak forces, electromagnetic forces, gravitational forces) in nature.

(3)Gravitational forces are always attractive . They are also conservative in nature. work done by these forces or against these forces doesn't depend on the path followed.

Explanation:

What mistake did Kamala make? Gamma rays should have a very high frequency, not a very low frequency. Visible light should have a low frequency and a long wavelength. Infrared light should have a short wavelength, not a long wavelength. Microwaves should have a high frequency and a short wavelength.

Answers

Answer:

The answer is "Option A".

Explanation:

Please find the complete question in the attached file.

Kamala uses Gamma radiation inside this question should be very high, not very low. Electromagnetic radiation is a penetrating type resulting from radioactive nuclear decline. Its radiation is a very high-frequency, radioactive waveform to frequencies greater than [tex]10^{19} \ Hz[/tex] usually emitted from the radioactive decline.

Answer:

A

Explanation:

edge 2022

Which of the following is evidence that a chemical reaction has occurred?

Answers

Change in color and change in temperature of energy as to being exo or endothermic

which word meaning sensible has the most negative connotation​

Answers

I’d say stuffy. It has the most negative connotation of all the options .

Answer:

I’d say stuffy. It has the most negative connotation of all the options .

Mark Brainlest please!

What conditions would probably exist the dew point and dry bulb temperatures to be the same at the ground ?

Answers

Answer: The conditions would probably exist the drew point and dry bulb temperatures to be the same at the ground because When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is NEVER GREATER than the air temperature. Therefore, if the air cools, moisture must be removed from the air and this is accomplished through condensation.

Explanation:

Since the air is said to be saturated when the dew point temperature and air temperatures are equal, the circumstances are likely present for the dew point and dry bulb temperatures to be equal at the ground. NEVER is the dew point temperature higher than that of the air temperature. As a result, condensation is used to remove moisture from the air when it cools.

What is dew point temperature?

The dew point, under the assumption of constant air pressure and water content, is the temperature at which air must be chilled to become water vapor condenses. Airborne vapor will condense to create liquid water, known as dew, when it is cooled below the dew point, thereby moisture capacity.  If this occurs via coming into contact with a cooler surface, dew will grow there.

Humidity influences the dew point. The dew point rises as the amount of moisture in the atmosphere increases.

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nt: what is the unit of measurement for work?)
A body builder lifts a 200kg barbell up 2m into the air. How
much work does the bodybuilder do?

Answers

Answer:

The unit of measurement of work is Nm which is also called as Joule and written J.

work done by the body builder against gravity = 3920J

Explanation:

work = force x displacement

force on barrel = 200 x gravity = 200 x 9.8 = 1960 N

displacement = 2m

work done against gravity = 1960 x 2 = 3920 J

Question- Gases the oceans exchange with the atmosphere include..

a. oxygen
b. carbon dioxide
c. water vapor
d. all of the above

Answers

I am pretty sure it’s B (carbon dioxide)

PLEASE HELP ME
Which refers to the amount of energy in a sound wave per unit of time and is also related to the loudness of a sound? period compression amplitude intensity

Answers

Answer: Thanks for the points!

Explanation:  The average amount of energy passing through a unit area per unit of time in a specified direction is called the intensity of the wave. As the amplitude of the sound wave increases, the intensity of the sound increases. Sounds with higher intensities are perceived to be louder.

Answer:

Amplitude

Explanation:

In a perfectly inelastic collision between two balls:

a) No changes happen to the internal structure of the balls

b) The total kinetic energy of the balls is conserved

c) The balls have the same velocity after the collision

d) The balls temperature does not change.

Answers

Answer:

c) The balls have the same velocity after the collision

Explanation:

In a perfectly inelastic collision between two balls, there is a loss in the maximum kinetic energy of the system and the two ball stick together, and thereby have the same velocity after the collision and also the coefficient of restitution of the two balls is also zero accompanied by a loss in the kinetic energy of the system

Therefore, the correct option is that both balls will have the same (equal) velocity after the collision.

Which one of the following is an example of an acid-base reaction?
A. 2HCl + Mg(OH)2 + 2H2O + MgCl2
B. Fe + CuSO4 → FeSO4 + Cu
C. 2Li + ZnSO4 → Li2SO4 + Zn
O D. C5H12 + 802 - 5CO2 + 6H20
No links please

Answers

Answer:

A. 2HCl + Mg(OH)2 + 2H2O + MgCl2

hope it helps

Which product forms from the synthesis reaction between calcium (Ca) and
chlorine (CI)?
A. CaCl2
B. CaCl
C. Ca2Cl2
O D. Caci
SUBMIT

Answers

Answer:

CaCl2

Explanation:

Answer:

its a! the answer is a

Explanation:

How many pieces of thin, light glass will have the same effect as one thick, dark glass?

Answers

Answer:

Explanation:

i would 3 thin light glass would have the same effect as one thick dark glass

Four pieces of thin, light glass will have the same effect as one thick, dark glass.

What is Glass ?

Glass is an inorganic solid substance that is generally transparent or translucent, as well as hard, brittle, and resistant to the elements. From ancient times, glass has been used to make utilitarian and aesthetic products, and it is now highly significant in uses as diverse as building construction, kitchenware, and telecommunications. It is created by rapidly chilling molten components such as silica sand to prevent the creation of visible crystals.

A quick discussion on glass follows. A lot of articles go into great length on glass. Stained glass and glassware explain stained glass and the aesthetic qualities of glass design. Industrial glass discusses the composition, characteristics, and industrial manufacture of glass. The physical and atomic properties of glass are discussed in amorphous solid.

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Studying this brochure from nasa, which explains more detail the instruments carried by the Juno spacecraft which scientific activities will jump conduct on its trip to Jupiter? Check all that apply

Answers

Answer:

Juno scientific payload includes:

A gravity/radio science system (Gravity Science) A six-wavelength microwave radiometer for atmospheric sounding and composition (MWR) A vector magnetometer (MAG) Plasma and energetic particle detectors (JADE and JEDI) A radio/plasma wave experiment (Waves) An ultraviolet imager/spectrometer (UVS) An infrared imager/spectrometer (JIRAM)

Explanation:

Each mission of NASA has a specific set of instruments that it uses to perform scientific experiments on the desired heavenly body. In case of Juno, the mission for Jupiter has a series of instruments that would study domains of gravitational forces, magnetic effect, particle detection, radiation detection, UV/IR imaging, and plasma experiments.

7. A train 100 m long is moving with the velocity of 72 km/h. Find the time it takes to cross the bridge which is 2 km long?
a) 1050 S
b) 10500 s
c) 10.5 s
d) 105 s

Answers

Answer:

d) 105 s

Explanation:

Given the following data;

Distance A (length of train) = 100 m

Velocity = 72 km/h to meters per seconds = 72 * 1000)/3600 = 72000/3600 = 20 m/s

To find the time;

Time = distance/speed

Time = 100/20

Time = 5 seconds.

II. When the distance (bridge) is 2km;

Distance B = 2km = 2*1000 = 2000 meters

Time = distance/speed

Time = 2000/20

Time = 100 seconds

Therefore, total time = 5 + 100 = 105 seconds

Several merchant ships reports rogue waves
which are estimated to be 25 meters high and 26 meters long. Assuming that these waves travel at
speeds of 6.5 m/s, determine the frequency and the period of these waves.

Answers

Answer:

The frequency is 0.25Hz and the period is 4s

Explanation:

To solve this we can use the formula: [tex]f = \frac{v}{\lambda}[/tex], where f=frequency, v=velocity and lambda = wavelength.

In the question, we are given the information that the velocity of the wave is 6.5m/s and the wavelength is 26 meters long. By putting these values into the formula, we can find the frequency:

[tex]f=\frac{6.5}{26} \\f= 0.25Hz[/tex]

Period is the inverse of frequency: [tex]T=\frac{1}{f}[/tex]

Therefore the period is: [tex]T = \frac{1}{0.25} \\T = 4s[/tex]

Hope this helped!

A 50-kg copper block initially at 140°c is dropped into an insulated tank that contains 90 l of water at 10°c. Determine the final equilibrium temperature and the total entropy change for this process.

Answers

Answer:

[tex]T_f=24.71[/tex]

Explanation:

From the question we are told that:

Mass of block [tex]m=50[/tex]

Temperature of block [tex]T_b =140 \textdegree C[/tex]

Volume of water [tex]V= 90L[/tex]

Temperature of water [tex]T_w=10 \textdegree C[/tex]

Density of water [tex]\rho=1000kg/m^3[/tex]

Specific heat of water [tex]C_w=4.18KJ/kg-k[/tex]

Specific heat of copper [tex]C_p=0.96KJ/kg-k[/tex]

 

Generally the equation for equilibrium stage is mathematically given by

[tex]mC_p(T_b-T_f)=\rho*VV*c(T_f-T_w)[/tex]

[tex]50*0.96(140-T_f)=1000*90*10^-3*c_w(T_f-10)[/tex]

[tex]48(140-T_f)=376.2(T_f-10)[/tex]

[tex]140-T_f=7.8375(T_f-10)[/tex]

[tex]140-T_f=7.8375T_f-78.375[/tex]

[tex]-8.8375T_f=-218.375[/tex]

[tex]T_f=\frac{-218.375}{-8.8375}[/tex]

[tex]T_f=\frac{-218.375}{-8.8375}[/tex]

[tex]T_f=24.71[/tex]

The lens of a telescope has a diameter of 25 cm. You are using it to look at two stars that are 2 × 1017 m away from you and 6 × 109 m from each other. You are measuring light with a wavelength of 700 nm. As the light goes through the lens, it diffracts. a. Is it possible, using this telescope, to see the two stars as separate stars? b. What is the minimum possible lens diameter you would need in order to resolve these two stars?

Answers

Answer:

a)It is NOT possible using this telescope, to see the two stars as separate stars

b)[tex]d_{min} =28.466m[/tex]

Explanation:

From the question we are told that:  

Diameter of lens,[tex]d = 25 cm \approx 0.25 m[/tex]

Distance from both star [tex]D_f= 2*10^{17} m[/tex]

Distance between both stars [tex]D_b= 6*10^9 m[/tex]

Wavelength of light [tex]\lambda =700 nm \approx 700*10^-9 m[/tex]

Generally the equation for angle subtended by the two stars at the lens  is mathematically given by

 [tex]\theta=\frac{D_f}{D_b}[/tex]

 [tex]\theta=\frac{6*10^9}{2*10^{17}}[/tex]

 [tex]\theta=3.0*10^{-8} rad[/tex]

Generally the equation for minimum angular separation of two object is mathematically given by

[tex]\theta_{min} = 1.22*\lambda/d[/tex]  

[tex]\theta_{min}= \frac{1.22*700*10^-9}{0.25}[/tex]  

[tex]\theta_{min}= 3.416*10^-^6 rad[/tex]

Therefore

 [tex]\theta < \theta_{min}[/tex]

[tex]3.0*10^{-8} rad< 3.416*10^-^6 rad[/tex]

It is NOT possible using this telescope, to see the two stars as separate stars

b)

Generally the equation for minimum diameter of the lens is mathematically given by

  [tex]d_{min} =\frac{ 1.22*\lambda}{\theta}[/tex]

  [tex]d_{min} =\frac{ 1.22*700*10^{-9}}{3*10^{-8}}[/tex]

  [tex]d_{min} =28.466m[/tex]

One way to think about circular motion is that the object is continuously ____________.
A. Prevented from moving in a straight line.
B. Allowed to move in a straight line.
C. Forced to move in a straight line.
D. Encouraged to move in a straight line.

Answers

Answer:

A

Explanation:

circular motion means the object will follow a circular trajectory.

Answer:

the answer for the question is option A

Which is NOT something that all green plants have in common?
1.They make their own food.
2. They reproduce.
3 .They grow.
4 .They produce flowers.

Answers

Answer:

4

Explanation:

Not all plants can grow flowers. Only the ones thay have buds can.

Not all plants produce flowers. Hence, this is the characteristic which is not common in all plants.Therefore, the correct option is 4.

What are flowers?

Flowers are the structures of plants. They are responsible for producing seeds that will grow into new plants. Flowers typically consist of a colorful or ornamental part called the corolla, which attracts pollinators such as bees and butterflies, and a reproductive part called the stamen and pistil, which contain the plant's male and female organs.

Not all green plants produce flowers. Flowering plants are a type of plant that belong to the group Angiosperms, but there are also non-flowering plants like ferns and mosses that do not produce flowers. Therefore, the correct option is 4.

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Ali mixes 20g of Sodium Chloride in 100g of water at 15 Degree °C. Calculate the mass of the solution

Answers

Answer:

The mass of the solution is 120 g.

Explanation:

The mass of the solution is given by:

[tex] m_{sol} = m_{1} + m_{2} [/tex]

Where:

[tex]m_{sol}[/tex]: is the mass of the solution

[tex]m_{1}[/tex]: is the mass of the solvent

[tex]m_{2}[/tex]: is the mass of the solute

In the solution, the solvent is the majority compound (in mass) and the solute is the minority (in mass), so the solvent is the water and the solute is sodium chloride.          

Hence, the mass of the solution is:

[tex] m_{sol} = m_{1} + m_{2} = 100 g + 20 g = 120 g [/tex]  

I hope it helps you!                  

How are frequency, wavelength, and energy related? Choose all that apply.

Answers

Explanation:

The energy of a wave is given by :

[tex]E=\dfrac{hc}{\lambda}[/tex]

Where

h is Planck's constant

c is the speed of light

[tex]\lambda[/tex] is wavelength

Energy is inversely proportional to wavelength. Also, the relation between frequency and wavelength is inverse.

If the frequency is high, the wavelength will be shorter.

Hence, the correct options are :

Higher frequencies have shorter wavelengths.

Shorter wavelengths have lower energy.

Lower frequencies have lower energy.

8. What is the frequency heard by a person driving at 15.0 m/s toward a blowing factory whistle (800. Hz) if the speed of sound is 340.6 m/s? (837 Hz) F= (340.6×800)÷(340.6-15)= 836.9 Hz F=836.9 9. From the previous problem, what frequency would he hear after passing the factory if he continues at the same speed? (766 Hz)

Answers

Answer:

A) f_o ≈ 836.9 Hz

B) f ≈ 765 Hz

Explanation:

A) To solve this, we will use the formula;

f_o = (v•f_s)/(v - v_p)

Where;

v is speed of sound in air

f_s is frequency of source

v_p is the speed of the person moving towards the whistle.

We are given;

v = 340.6 m/s

v_p = 15 m/s

f_s = 800 Hz

Thus;

f_o = (340.6 × 800)/(340.6 - 15)

f_o ≈ 836.9 Hz

B) to solve this, let's first calculate the wavelength from the formula;

λ = v/f_s

λ = 340.6/800

λ = 0.42575 m

To get the frequency he will hear after passing the factory, we will use the formula;

f = (v - v_p)/λ

f = (340.6 - 15)/0.42575

f ≈ 765 Hz

a student had rolled 114 dice and removed all those landed on the number six. the student rolled the remaining dice again and removed those that landed on a six. when the student had rolled the dice 20 times there were 9 dice left.

Calculate the most likely number of times that the student had rolled the dice before the number of dice had halved.​

Answers

Answer:

4 rolls

Explanation:

The probability of rolling a 6 is 1/6 = 0.1667 (4.d.p)

This means that approx. 1/6 of the dice will land on a 6.

If the student removes a 1/6 of the dice each time, it means that the number of dice is decreasing by 1/6 each roll (or multiplying by 5/6).

114/2 = 57

By multiplying 114 by 5/6 and continuing we can see how many times it takes for us to get past 57.

Roll 1: 114 x 5/6 = 95

Roll 2: 95 x 5/6 = 79.17

Roll 3: 79.17 x 5/6 = 65.97

Roll 4: 65.97 x 5/6 = 54.98

Most likely to take 4 rolls before halving the number of dice.

You could also solve this problems by writing an equation and solving using logs but I think this method is easier to understand.

Hope this helped!

What are the four major tasks of the digestive system?


Ingestion, Digestion, Absorption, Elimination.


Ingestion, Procrastination, Absorption, Face the Nation.


Congestion, Progestion, Ingestion, Elimination

Answers

Answer:

Option A

The four major tasks of the digestive system are - Ingestion, Digestion, Absorption, Elimination

Explanation:

A digestive system has primarily four main functions

a) Motility - In this the food is ingested through opening in the form of mouth and then it starts moving from the mouth via esophagus to the stomach

b) Digestion - In the stomach, the food gets digestion and then it is passed on to the intestine

c) Absorption - In the small intestine essential nutrients and water is absorbed

b) Secretion - The waste remaining after intestine digestion is passed on to the rectum for secretion

Hence, option A is correct

A book that weighs 20 N sits on a table. How big and in what direction does the force of gravity from the Earth act on the book?
A. 20 N down
B. 10 N down
C. 20 N up
D. 10 N up

Answers

Answer:

A. 20 N down

Explanation:

It's asking how much force of gravity is acting on it. The book weighs 20 Newtons so that's how much gravity is being applied. Hope this helps

When a book that weighs 20 N sits on a table. then the force of gravity from the Earth acts on the book would be 20 N down, therefore the correct option is A.

What is gravity?

It can be defined as the force by which a body attracts another body towards its center as the result of the gravitational pull of one body and another, The gravity varies according to the mass and size of the body for example the force of gravity on the moon is the 1/6th times of the force of gravity on the earth.

When an object is thrown straight up in the absence of air resistance there is no external force acting on it except the gravitational force of the earth which very much reflects the fact that the acceleration due to gravity is constant and is the result of the gravitational pull of the earth which act on the downward direction.

A book that weighs 20 N sits on a table and faces a downward force of 20N acts on the book because the force of gravity from the Earth acts on the book.

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Calculate the pressure exerted on the floor by the boy standing on both feet if the weight of the boy is 40kg. Assume that the area of each of his shoes is 6cm x 25cm.
(Take 1kg of weight = 10N)

Answers

Answer:

P = 1333.33 N

Explanation:

The pressure exerted by the boy on the floor can be calculated by the following equation:

[tex]P = \frac{F}{A}[/tex]

where,

P = Pressure exerted by the boy = ?

F = Force Applied = Weight of Boy = 40 kg = 40 N (since 1 kg = 1N)

A = Area of application of force = 2(Area of one show) = 2(6 cm x 25 cm)

A = 2(0.06 m x 0.25 m) = 0.03 m²

Therefore,

[tex]P = \frac{40\ N}{0.03\ m^2}\\\\[/tex]

P = 1333.33 N

Reo performed an experiment to investigate the strength of an electromagnet and the amount of force that would be affected by the size of the current flowing through its coils. Which of the following changes would increase the current flow the most?

a. Decreasing the number of paper clips being picked up
b. Decreasing the number of coils of wire wrapped around the nail
c. Increasing the voltage power supply
d. Increasing the number of nails



(WILL GIVE BRAINLIEST)

Answers

Answer:

b. Decreasing the number of coils of wire wrapped around the nail

it can cause an electrical current running through it creates a magnetic field.

Other Questions
Please help!!How do I write the inversion of these questions in french1. Est-ce quil fair ses devoirs?2. Avec qui est-ce que tu tudies? Great Landscapes Company estimates its doubtful accounts by aging its accounts receivable and applying percentages to various aged categories of accounts. The Great Landscapes Company computes a total of $3,600 in estimated doubtful accounts as of December 31, 2019. Its Accounts Receivable account has a balance of $112,800 and its Allowance for Doubtful Accounts has a credit balance of $600 before adjustment at December 31, 2019. How much bad debts expense will Great Landscapes report in 2019 the area of a circle is 0.2826 square miles. what's is the circle's radius? use 3.14 for pi state the type of enthalpy in the followinv equation Koh+Hcl-kcl+h2o h+=-57kj\mol explain how at least three pieces of evidence support the theory of evolution What is assemblage? How is this approach different from other forms of sculpture?What choices do artists make when they create an assemblage? What is the impact of those choices? Cause of bronchiectasis The probability of randomly selecting a white flower from a garden that has green, pink, yellow, and white flowers is 3%.Which of the following describes the likelihood of selecting a white flower?A. likelyB. unlikelyC. neither unlikely nor likely Plz helppp Differentiate between prefixes and suffixes. 1. A continuacin, encontrara los nombres de algunos organismos, las sustancias que excretan y la utilidad de susexcreciones. Aplique el mismo color a los dos elementos que tengan relacin entre s.Bacterias aerobias produccin de yogur y vinagreBacterias anaerobias dixido de carbono y aguaProtozoos cido lctico o cido acticoAlgas alcohol etlicoLevaduras Dixido de carbonoHongos multicelulares oxigeno durante el da como producto de la fotosntesis Calculate the heat gained when 20.1 g ice at - 12.5 degrees * C is heated to liquid water 55.2 degrees * C Which of the atomic models represents the most reactive element?A. Argon, because it has three energy levels with eight electrons in the third level.B. Lithium, because it has two energy levels with one electron in the second level.C. Aluminum, because it has five energy levels with two electrons in the third level.D. Carbon, because it has two energy levels with four electrons in the second level. Checks and Balances, Match the definition (Letters) with the wordFor example: 1. C you X-10-25-55101520-20-15-5 6. Name one way the state of New Mexico supports tribal economies. simplifying expressionsthis is a whole page of questions and i dont remember how to do them pls help if you know any of them 1. 12m + 24m2. 90a - 30a3. 14b + 15b + 84. 58d + 25 - 22d5. 3(14 + 15f) + 796. 20(18 + 5t) - 47 + 28t Read this message from Assistant Principal Amy Gaskell.To all Faculty, Staff, Students, and Parents:As Principal Kohl has written, I am leaving the Armstrong School to become the principal of another school. While I am thrilled about that new challenge, I also feel sad about leaving our school. I will miss each and every one of you. I will carry the friendships and memories Ive made here with me forever. Thank you all for being so wonderful!What is the writers attitude? A. angry and frustrated B. excited and sorrowful C. worried and thoughtful D. surprised and grateful HELP PLEASE Why does it matter that we protect African Wild Dogs? How did Jefferson feel the purchase wouldaffect the U.S. ? How many ways can three people be selected from a group of seven people if order DOES matter?