List two things you should not do when giving a presentation

Answer:

If enough evidence accumulates to support a hypothesis, it moves to the next step (known as a theory) in the scientific method and becomes accepted as a valid explanation of a phenomenon.

Answer:

Hypothesis is usually referred as an assumption or an observation made without much proof to support the statement. Hence scientists and experimental physicists uses hypothesis and perform experiments and observations to support the theory.

The hypothesis will get transformed into a theory only when there is enough evidence to support the cause and the science behind the set of events. It is dependent upon a number of scientific tests an hence it is not possible to define a time period. It may varies from years to forever (or never).

Answer:

Balance forces are two forces acting in opposite directions on an object, and equal in size. Anytime there is a balanced force on an object, the object stays still or continues moving continues to move at the same speed and in the same direction.

Explanation:

pls thank me

Answer:

Balance forces are two forces acting in opposite directions on an object, and equal in size.

Answer:

0.900 mol/kg

Explanation:

Molality is moles of solute per kilograms of solvent.

Converting 54 grams of NaOH to moles:

54 g NaOH × (1 mol NaOH / 40.00 g NaOH) = 1.35 mol NaOH

So the molality is:

m = (1.35 mol) / (1.50 kg)

m = 0.900 mol/kg

Convert grams of NaOH to moles:

The formula to convert grams to moles is:[tex]\text{moles of NaOH} = \frac{\text{mass of NaOH (g)}}{\text{molar mass of NaOH (g/mol)}}[/tex]

Given that the mass of NaOH is 54 grams and its molar mass is 40.00 g/mol:

[tex]\text{moles of NaOH} = \frac{54 \text{ g}}{40.00 \text{ g/mol}} = 1.35 \text{ moles}[/tex]

Determine the mass of the solvent (water):

The mass of water is given as 1.50 kg.

Convert this mass into kilograms (if necessary):

Since 1.50 kg is already in the correct unit, no conversion is needed here.

Calculate molality (m):

The formula for molality is:

[tex]\text{molality (m)} = \frac{\text{moles of solute}}{\text{mass of solvent (kg)}}[/tex]

Substitute the values into the formula:

[tex]\text{molality} = \frac{1.35 \text{ moles}}{1.50 \text{ kg}} = 0.90 \text{ m}[/tex]

Answer:

a) Both balls are affected by gravity in the same way. The time both balls hit each other is equal to the time the ball thrown up reaches the top of the roof, if there was no gravity. (both balls would be at the same location)

y = v*t = 85m = 46m/s * t

t = 1.85s

Check:

The equation for position is given by:

y(t) = -0.5gt² + v₀t + x₀

The position of the ball on the roof top at time t = 1.85s:

y₁(t) = -4.9t² + 85.0 = 68.3m

The position of the ball thrown up at time t = 1.85s:

y₂(t) = -4.9t² + 46 * 1.85 = 68.3m

b) the two balls hit each other at a hight of 68.3m

The ball dropped from the building hits the ground after approximately 4.16 seconds. The ball thrown upward from the ground hits the ground after approximately 9.39 seconds. Both balls hit at the ground level.

This question involves the concepts of motion in Physics. We'll use the formulas for kinematic motion to find out when and where the two balls hit. First, let's consider the ball that's dropped.

The ball drops with an initial speed of 0 m/s as the ball is released from rest and it will cover a distance of 85.0 meters under the acceleration due to gravity. We use the second equation of motion: s = ut + 0.5gt^2. Here, s is the displacement (85 meters), u is the initial speed (0 m/s), g is the acceleration due to gravity (9.8 m/s^2), and t is the time we wish to determine. Plugging the known values, we find t = sqrt(2s/g) which gives us t ≈ 4.16 seconds.

Now for the ball thrown upwards from the ground with an initial speed of 46.0 m/s. The ball goes upwards, then slows down, stops and starts falling down under gravity. The time when the ball hits the ground is twice the time it takes for the ball to reach the highest point. That time is given by t = u/g (since at the highest point, final velocity is 0). Thus, the total time is T = 2u/g, which gives us T ≈ 9.39 seconds.

As for where they hit, the ball dropped from the building hits the ground, and the ball thrown upwards from the ground hits the ground again after it reaches the maximum height and falls back.

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Answer:

a. change in state

Explanation:

Separation of iron filings from its mixture with sulphur is an example of mixing and separation.

Answer: B.  mixing and separation

Explanation:

Separation techniques exploit various physical and chemical properties of substances. When a mixture undergoes separation it may result in two or more mixtures or even pure substances. Here separation of iron filings is achieved by making use of the magnetic property of iron.

Very few substances occur in pure form in nature. In order to obtain pure substances various separation techniques have to be employed. Examples of separation techniques are chromatographic separation, centrifugation, electrophoresis etc...

1.

Answer:

m = 74.9 kg

Explanation:

As we know that weight of the object is force due to gravity

Now we know that

[tex]F_g = mg[/tex]

[tex]m = \frac{F_g}{g}[/tex]

[tex]m = \frac{735}{9.81}[/tex]

[tex]m = 74.9 kg[/tex]

2.

Answer:

[tex]s = 450 J/kg ^oC[/tex]

Explanation:

Heat added to the system is given as

[tex]Q = ms\Delta T[/tex]

so we will have

[tex]337500 = 50 s (15)[/tex]

[tex]s = 450 J/kg ^oC[/tex]

3.

Answer:

Velocity will increase while acceleration will remain constant

Explanation:

When skydiver falls from rest then velocity will increase with time while the acceleration due to gravity will remains constant.

So here we can say that

[tex]a = 9.81 m/s^2[/tex]

while velocity will increase while it falls from certain height

The answer is D: The total number of protons and neutrons is 15.

The atomic mass of an atom is the total mass of its protons and neutrons. Protons have a mass of 1 amu, and neutrons have a mass of 1 amu. Therefore, if an atom has an atomic mass of 15 amu, then it must have 15 protons and 15 neutrons.

A: There are 15 protons. This is not necessarily true. The atomic number of an atom is the number of protons in its nucleus. The atomic number of an atom with an atomic mass of 15 could be 7 (nitrogen), 8 (oxygen), or 9 (fluorine).

B: There are 15 electrons. This is not necessarily true. The number of electrons in an atom is equal to the number of protons in the atom's nucleus. However, the electrons can be arranged in different energy levels, so the number of electrons in the outermost energy level may not be equal to the number of protons.

C: The total number of protons and electrons is 15. This is not necessarily true. The number of protons in an atom is always equal to the number of electrons in the atom. However, the number of electrons in the outermost energy level may not be equal to the number of protons.

D: The total number of protons and neutrons is 15. This is always true. The atomic mass of an atom is the total mass of its protons and neutrons. Therefore, if an atom has an atomic mass of 15 amu, then it must have 15 protons and 15 neutrons.

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Answer:

I think it's D) Guess why? I searched it up!

Answer:

143.325 pounds (rounded to 8 digits, but you can round it to a lower amount of digits if you need to!)

Explanation:

So 1 kg = 2.205 lbs, so 65 kg = 2.205lbs * 65kg, which is equal to approximately 143.325 lbs.

( 1kg = 2.205lbs; 65 kg = ? lbs)

Answer:

circle graph

Explanation:

A circle graph it is a statistical resource that is used to represent percentages and proportions. The number of elements compared within this graph can range from two to as many as required. Thus, Using this graph you can visualize the proportion of each expense, like food and housing, with respect to the total monthly income.

Answer:

circle graph

Explanation:

did the test

Answer:

period

Explanation:

Answer:

The time required for one cycle, a complete motion that returns to its starting point, is called the period .

Explanation:

Any motion that repeats at regular time intervals is called periodic motion. This kind a motion has some characteristics like the period. Other important characteristic is the frequency, which is the number of complete cycles in a given time, that is, the inverse of the period.

Explanation:

Given , F = 30N and mass m = 90kg

°•° F = ma

=> a = F/m

=> a = 30/90

=> a = 1/3m/s^2

Final answer:

To find the acceleration of a 90 kg box with a force of 30 N applied, use Newton's second law of motion. The acceleration is calculated as 0.333 m/s².

Explanation:

To calculate the acceleration of a 90 kg box when a force of 30 N is applied, we can use Newton's second law of motion, which is F = ma, where F is the force applied, m is the mass of the object, and a is the acceleration of the object. Rearranging the equation for acceleration gives us a = F / m.

In this case, F = 30 N and m = 90 kg. Plugging these values into the equation yields a = 30 N / 90 kg = 0.333 m/s². Therefore, the acceleration of the box is 0.333 meters per second squared (0.333 m/s²).

From hide-out toward prey:

Speed = 18 km/hr=5 m/s. ... Time = 2.5 sec. ... Distance= s*t = 12.5 meters

From turn-around back to hide-out:

Distance = 12.5 m. ... Time = 12.0 sec

Average speed = (total distance covered) / (time to cover the distanced)

total distance = (12.5 + 12.5) = 25 meters

total time = (2.5 + 12.0) = 14.5 sec

Average speed = (25 m) / (14.5 sec) = 1.72 m/s

Average velocity = displacement / time

The creature ended up where it started, so its displacement is zero.

Average velocity = ( 0 / 14.5 sec )

Average velocity = zero

The snake then turns around and slowly returns to its hide-out in 12.0 s, mamba's average velocity for the complete trip is approximately 1.72 m/s.

By taking into account both the mamba's initial speed towards the prey and its subsequent motion back to the hiding place, the average velocity of the entire journey can be computed.

First, let's convert the velocities to meters per second (m/s):

[tex]\[ \text{Initial velocity} = 18.0 \, \text{km/h} \\\\= \frac{18.0 \times 1000}{3600} \, \text{m/s}\\\\ \approx 5.0 \, \text{m/s} \][/tex]

The distance traveled towards the prey can be calculated using the formula [tex]\( \text{Distance} = \text{Velocity} \times \text{Time} \)[/tex]:

[tex]\[ \text{Distance towards prey} = 5.0 \, \text{m/s} \times 2.50 \, \text{s} \\\\= 12.5 \, \text{m} \][/tex]

The distance traveled back to the hide-out is the same as the distance towards the prey:

[tex]\[ \text{Distance back to hide-out} = 12.5 \, \text{m} \][/tex]

The total distance traveled for the complete trip is twice the distance towards the prey:

[tex]\[ \text{Total distance} = 2 \times 12.5 \, \text{m} \\\\= 25.0 \, \text{m} \][/tex]

The total time taken for the complete trip is the sum of the time towards the prey and the time back to the hide-out:

[tex]\[ \text{Total time} = 2.50 \, \text{s} + 12.0 \, \text{s} \\\\= 14.5 \, \text{s} \][/tex]

[tex]\[ \text{Average velocity} = \frac{25.0 \, \text{m}}{14.5 \, \text{s}}\\\\ \approx 1.72 \, \text{m/s} \][/tex]

Thus, the mamba's average velocity for the complete trip is approximately [tex]\(1.72 \, \text{m/s}\)[/tex].

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Answer:

It takes the bird 0.6875 hour to fly 22 km

Explanation:

Lets revise the relation between the distance, speed and time

→ Distance = speed × time

→ Speed = distance ÷ time

→ Time = distance ÷ speed

A bird can fly at 32 km/h

The speed of the bird is 32 km/h

The bird will fly 22 km

We need to find the time it takes the bird to fly this distance

The speed = 32 km/h

The distance 22 km

Lets use the rule:

→ Time = distance ÷ speed

→ Time = 22 ÷ 32 = 0.6875 hour

It takes the bird 0.6875 hour to fly 22 km

The correct option that determines gravitational pull is mass. Gravitational force is calculated using the masses of objects and the gravitational constant, with the formula F = mg close to the Earth's surface.

Gravitational pull and Influencing Factors

The option that determines gravitational pull is mass. According to Newton's Law of Gravity, anything that has mass attracts everything else that has mass. The gravitational force (F) between two objects can be determined by the equation F = G(M1M2)/r^2, where G is the gravitational constant, M1 and M2 are the masses of the objects, and r is the distance between the centers of the two objects. The force of gravity on an object near the Earth's surface is calculated as the mass of the object (m) multiplied by the acceleration due to gravity (g), which is F = mg.

Volume does not directly determine gravitational pull; rather, it is the total quantity of matter, or mass, within that volume that contributes to gravity. The acceleration due to gravity remains constant (g = 9.81 m/s^2 near the Earth's surface) regardless of the object's mass. While the force of gravity is relatively weak, it is sufficient to keep the planets in orbit around the sun, as demonstrated in Newton's Universal Law of Gravitation.

Answer:

Explanation:

First, since the engineer is a slowpoke and he reacts a third of a second too late, the train will have 330 - 0.29*25 = 322,75 meters to stop. now, be [tex]x[/tex] (with [tex]x>0[/tex]) the deceleration value for which the train bumps at the car and stops, you have two conditions:

[tex]\left \{ {{25t-\frac12xt^2 = 322.75} \atop {0=25-xt}} \right.[/tex]

First states how much space the train has to stop, and the second tetermines how fast it slows down.

Solving the second for t, substituting in the first, and solving for x gives you a value of approximately [tex]1.94 m/s^2[/tex].

As usual, double check the calculations for yourself, it's always a good practice

Answer:

your mass is the same in the moon as on earth

Explanation:

on the monn there is less gravity than in the earth gravity determines the weight of an object but it can't change mass as mass is the amount of contents inside with out gravity

Final answer:

C) Your mass remains the same on the Moon as it is on Earth because mass is a measure of the amount of matter and does not change with location. However, your weight would be less on the Moon due to the weaker gravitational force compared to Earth's gravity.

Explanation:

When it comes to your mass on the Moon compared to your mass on Earth, your mass stays exactly the same in both locations. This is because mass is a measure of the amount of matter in an object, which does not change with location. On the other hand, weight is the force exerted on your mass by gravity, and this force does vary with location due to differences in gravitational pull.

Since the gravitational acceleration on the Moon is only about 1.625 m/s², compared to Earth's 9.80 m/s², your weight on the Moon would be significantly less than your weight on Earth, even though your mass remains unchanged. Therefore, if you were to scale, you would see a lower number on the Moon. Remember that while dieting might reduce your mass, simply stepping onto the Moon's surface only affects your weight, not your mass!

To conclude, the correct answer is:C) Your mass is the same on the Moon and Earth

Answer:

Kinetic energy is energy in motion so therefor if you increase the velocity or in your case speed the kinetic energy also has to increase

Explanation:

Answer:

If the speed of a motorbike increases, its kinetic energy will also increase.

Explanation:

Kinetic energy is the energy an object has due to its motion, and it is a function of the mass and velocity of the object:

[tex]E_{k}=\frac{m*v^{2}}{2}[/tex]

From the expression, it is easy do identify a quadratic relation between kinetic energy and velocity. Therefore, if the speed of a motorbike increases, its kinetic energy will also increase.

For example, if you increase the speed of a motorbike by 10 times, and since mass is a constant value, the kinetic energy will increase by 100 times.

All three of Newton's laws of motion, as well as his law of universal gravity, are involved in the explanation of orbits.

Answer:

97% will sink below the water

Explanation:

Waters density is 1 g/cm3

If an object's density is greater than 1g/cm3, it will sink. If it's less then it would float. 1-0.97 = 0.03. Only 3% of the ice would show while 97 will be under.

Answer:

About 97 percent of the ice will sink below water.

Explanation:

Let the volume that is submerged into the water is given as V1

so at equilibrium condition we can say that buoyancy force on it is balanced by weight of the block

so we have

[tex]\pho_{water} V_1 g = \rho_{ice} V g[/tex]

now we have

[tex]\frac{V_1}{V} = \frac{\rho_{ice}}{\rho_{water}}[/tex]

[tex]\frac{V_1}{V} = \frac{0.97}{1}[/tex]

so the percentage of block that is submerged into the water is given as

volume percent submerged = 97 %

The natural sources of water pollution are algae blooms.

Answer: Option C

Explanation:

The natural form of water pollution is due to water erosion, the composition of minerals, leaves, human/animal droppings, etc. Algae blooms are the development of phytoplankton (a tiny floating plants in fresh and salt water).

Algae bloom also causes problems in the aquatic ecosystem. The excessive algae can block sun rays and hence affect important aquatic habitats.

This can also be seen in the fish gills and inhibit their breathing. When a significant bloom of algae dies, they can damage the available oxygen in the water and make it uninhabitable for other life forms.

Answer:

C. Algae blooms

Explanation:

Algae blooms grow largely and rapidly in fresh and marine water. It discolors the water. These can produce toxins in water and are very harmful for marine life as it blocks the sunlight from reaching the depth. Also, marine life struggles to find food and eventually leaves the area. It also badly impacts the local economy. It is the natural source of water pollution.

The intensity of X-ray beam of second exposure made at 100 cm SID is 20 mR.

Solution:

By using inverse square law formula, intensity of X-Ray beam made at different distances can be found.

[tex]\frac{I_{1}}{I_{2}}=\left(\frac{D_{2}}{D_{1}}\right)^{2}[/tex]

Where [tex]I_1[/tex] is the intensity of first exposure of X-ray-beam.

[tex]I_2[/tex]  is the intensity of second exposure of X-ray beam.

[tex]D_1[/tex]  is the distance at which first exposure is made.  

[tex]D_2[/tex]  is the distance at which second exposure is made.

[tex]\begin{array}{l}{\frac{I_{1}}{I_{2}}=\left(\frac{100}{200}\right)^{2}} \\\\ {\frac{5}{I_{2}}=\frac{1}{4}} \\\\ \bold{{I_{2}=20\ \mathrm{mR}}\end{array}}[/tex]

Answer:

keep it and use it in similar assignments

Explanation:

A personal strategy card is a form of student assessment where teachers can look at the learning process of the student and get a feedback on the next learning step to be taken by the student.

The card can a sections are;

This information is important because it can be used as a study guide on other similar assignments .

Answer:

2.9

Explanation:

9.7 / 3.33 = 2.912912912...

We need to round to the correct number of significant figures.  9.7 has two significant figures, and 3.33 has three significant figures.  We need to round to the least number of significant figures available, so we round to two.

2.91 ≈ 2.9

Answer:

I am pretty sure that the answer would be a peer reviewed article.

Explanation:

I saw this because, an encyclopedia, published scientific journal, and a lab journal used in the original experiment, are all reliable sources of information.

Answer:

A dictionary

Explanation:

did the quiz

Answer:

Physics

Chemistry

Explanation:

Physical science is science which studies non-living things.This covers things on earth to the universe.The main branches are physics and chemistry.The other sub-branches are Astronomy, meteorology and Geology.Physics is concerned with the basic principals of matter and energy.It covers concepts in motion, energy, force, pressure , light and many other areas we encounter in our day to day life.Chemistry is concerned with composition of matter and how it reacts.Material in chemistry is understood through observing molecules, atoms, elements and their interaction in nature including their properties.Chemistry is further divided into organic chemistry and natural chemistry sub-branches.

Explanation:

In a vacuum (no air resistance), it doesn't.  All falling objects, regardless of mass, accelerate at the same rate.

However, when air resistance is taken into account, heavier objects indeed fall faster than lighter objects, provided they have the same shape and size.  For example, a lead ball falls faster than a styrofoam ball.

To understand why, first look at what factors affect air resistance:

D = ½ρv²CA

where ρ is air density,

v is velocity,

C is drag coefficient,

and A is cross sectional area.

As falling objects accelerate, they eventually reach a maximum velocity where air resistance equals weight.  This is called terminal velocity.

D = W

½ρv²CA = mg

v = √(2mg/(ρCA))

If we increase m while holding everything else constant, v increases.  So two objects with the same size and shape but different masses will have different terminal velocities, with the heavier object falling faster.

Before you ask why, you need to know whether.

On the moon, or any other airless body, all objects fall together, no matter how much each one weighs. We've known this for a good 500 years.

On Earth, if one object falls slower, it's only because the air caught it and held it back.

Answer:

6 m/s

Explanation:

a) C. 9 m/s

First of all, let's calculate the difference in height between the starting point of the motion and the end point of the first section. It is given by:

[tex]\Delta h = L sin \theta[/tex]

where

L = 6.0 m

[tex]\theta=45^{\circ}[/tex]

Substituting,

[tex]\Delta h = (6.0)(sin 45^{\circ})=4.2 m[/tex]

Assuming the rider starts from rest, its initial speed is zero. For the law of conservation of energy, the decrease in gravitational potential energy of the rider will be equal to its gain in kinetic energy, so we can write:

[tex]mg\Delta h = \frac{1}{2}mv^2[/tex]

where m is the rider's mass, g = 9.8 m/s^2 is the acceleration of gravity, and v is the speed at the end of the first section. Solving for v, we find:

[tex]v=\sqrt{2g\Delta h}=\sqrt{2(9.8)(4.2)}=9.1 m/s \sim 9 m/s[/tex]

b) B. Increase the radius of the circular segment

In fact, the acceleration during the second section of the motion (circular motion) is given by the formula for the centripetal acceleration:

[tex]a=\frac{v^2}{r}[/tex]

where

v is the speed at the end of the first section

r is the radius of the circle

We notice that the acceleration is

- Proportional to the square of the speed

- Inversely proportional to the radius

So, we immediately see that if we increase the radius of the circle (choice B), the acceleration will decrease.

c) B. 3.4 m/s

When the rider exits the second section of the motion, he has a speed (completely horizontal) of 9.1 m/s (calculated in part (a); it didn't change, because the speed during the second section does not change).

The vertical component of his velocity is instead zero, since his motion is completely horizontal. Therefore, we can use the following SUVAT equation along the vertical direction:

[tex]v_y^2 - u_y^2 = 2g\Delta h[/tex]

where

[tex]v_y[/tex] is the vertical component of the velocity as the rider hits the water

[tex]u_y=0[/tex] is the vertical component of the velocity as the rider starts the 3rd section

[tex]\Delta h = 0.60 m[/tex] is the difference in height

Solving for [tex]v_y[/tex],

[tex]v_y = \sqrt{2g\Delta h}=\sqrt{2(9.8)(0.60)}=3.4 m/s[/tex]

d) C. 2.4 m

We want here the rider to land twice as far compared to before.

The horizontal distance travelled by the rider in section 3 is entirely determined by his horizontal motion. The horizontal component of the velocity, which is constant, is

[tex]v_x = 9.1 m/s[/tex]

calculated at part (a) and remained unchanged during section 2. The horizontal distance travelled during section 3 is

[tex]d=v_x t[/tex] (1)

where t is the time of the fall. This can be rewritten as

[tex]t=\frac{d}{v_x}[/tex]

We also know that the vertical displacement is:

[tex]h=\frac{1}{2}gt^2[/tex]

Substituting t from (1) into this equation, we find

[tex]h=\frac{gd^2}{2v_x^2}[/tex]

So we see that the height needed is proportional to the square of the distance: [tex]h \propto d^2[/tex]. Therefore, in order to land at twice the previous distance, the height must be 4 times the previous one, so:

[tex]h=4 (0.6 m)=2.4 m[/tex]

e) B. The second

We need to calculate the acceleration in each section.

In section 1 (motion along the slope), it is:

[tex]a=g sin \theta = (9.8)(sin 45^{\circ})=6.9 m/s^2[/tex]

In section 2 (circular motion), the acceleration is the centripetal acceleration:

[tex]a=\frac{v^2}{r}=\frac{9.1^2}{1.5}=55.2 m/s^2[/tex]

In section 3, the motion is free fall, so the acceleration is equal to the acceleration of gravity:

[tex]a=g=9.8 m/s^2[/tex]

Therefore, the rider experiences the largest acceleration in section 2.

This answer explains how to calculate the speed, acceleration, and vertical component of velocity for a rider on a water slide, as well as how to adjust the height to change the landing distance and determine the section with the greatest acceleration.

To answer these questions about the rider on the water slide, we need to use the formula for acceleration in circular motion, which is a = v2/r. For question a, we can use the given information to calculate the speed at the end of the first section of motion. For question b, reducing the radius of the circular segment would decrease the acceleration during the second section. For question c, we need to calculate the vertical component of the rider's velocity as he hits the water. For question d, we can use the concept of projectile motion to determine the necessary height above the water to land twice as far away. Finally, for question e, we need to determine during which section of the motion the magnitude of the acceleration experienced by the rider is the greatest.

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Answer: Ionization energy is the amount of energy necessary to remove an electron from an atom

Explanation:

Ionization consists of the production of ions, which are electrically charged atoms or molecules due to the excess or lack of electrons with respect to a neutral atom or molecule.

In this sense, ionization energy is the energy necessary to separate (remove) an electron from a gaseous atom, isolated and in a fundamental state. This is because electrons are strongly attracted to the nucleus and it is necessary to provide energy to separate them. However, where the atom always loses electrons is in the last layer, which is where the weakest electrons are attracted to the nucleus.