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Naturally occurring Uranium: 99.2745 %

Nuclear fuel for power generation: 97%

Nuclear bombs: 90 %

With a relative abundance of 99%, uranium-238 (238U or U-238) is the most prevalent isotope of uranium to be discovered in nature. It is non-fissile, unlike uranium-235, hence it cannot support a chain reaction in a thermal-neutron reactor.

A 1000 MWe pressurized water reactor needs about 27 tonnes of uranium per year, or over 18 million fuel pellets contained in more than 50,000 fuel rods. In contrast, a coal power plant of comparable scale would require more than 2.5 million tonnes of coal to generate the same amount of electricity.

15 kilograms: weight of a solid sphere of 100 percent uranium-235, just large enough to reach a critical mass with a beryllium reflector, nuclear weapons normally use a concentration of more than 90 percent.

Hence, the percentages are 99.27, 97 and 90% respectively.

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The mass number of an atom is defined as the sum of the number of protons and the number of neutrons in that atom.

So, if m is the mass number, p is the number of protons and n is the number of neutrons, we have:

We have that:

So, the mass number is 64.

ANSWER

The theoretical yield of Fe is 109.64 grams

EXPLANATION

Given that;

The mass of Fe2O3 is 192 grams

The mass of CO is 82.5 grams

Follow the steps below to find the theoretical yield of Iron

Steps 1; Find the number of moles of Fe2O3 and CO using the below formula

Recall, that the molar mass of Fe2O3 and CO are 159.69 g/mol and 28.01 g/mol

Step 2; Determine the limiting raectant of the reaction

To determine the limiting reactant, divide the number of moles by the co-efficient of each reactant

From the calculations, the limiting reactant of the reaction is CO

Step 3; Find the number of moles of Fe using a stoichiometry ratio

Let x represents the number of moles of Fe

The number of moles of Fe is 1.963 moles

Step 4; Find the theoretical yield of Fe

Recall, molar mass of Fe is 55.845 g/mol

Therefore, the theoretical yield of Fe is 109.64 grams

Answer:

The final temperature is 3,952K. (The closest option is 3,950K).

Explanation:

The given information from the exercise is:

- Initial pressure (P1): 300.6mmHg

- Initial volume (V1): 1.23L

- Initial temperature (T1): 218.5K

- Final volume (V2): 8.32L

- Final pressure (P2): 802.75mmHg

We can calculate the final temperature (T2), by replacing the values of P1, V1, T1, V2 and P2 in the following formula of Ideal Gases:

So, the final temperature is 3,952K. (The closest option is 3,950K).

Answer:

c

Explanation:

boulder was at rest on top of a hill so it contains abundant potentialenergy. When the boulder falls, its potential energy will change to kinetic energy, the energy of motion. When the boulder stops moving, its kinetic energy will transform back to potential energy

Answer:

Q = -5,365 J    

Explanation:

To find the amount of heat released, you need to use the following equation:

Q = mcΔT

In this equation,

-----> Q = heat (J)

-----> m = mass (g)

-----> c = specific heat capacity (J/g°C)

-----> ΔT = T₂ - T₁ = change in temperature (°C)

"T₂" represents the final temperature and "T₁" represents the initial temperature. You can plug the given values into the equation and solve to find "Q".

Q = ? J                         c = 2.9 J/g°C

m = 50 g                     ΔT = 18°C - 55°C = -37°C

Q = mcΔT                                               <----- Given equation

Q = (50 g)(2.9 J/g°C)(-37°C)                  <----- Insert values

Q = -5,365 J                                          <----- Multiply

*the answer is negative because the reaction is exothermic (heat is being released from the system)

Solubility of LaF3: "S"

First, we need to write the reaction of solubility:

LaF3 (s) <=> La+3 + 3 F-

Initial - 0 +0.011 (F-, from KF)

Change +S +3.S

Equilibrium S 0.011 + 3.S

Now, we know:

Ksp = [La³⁺]x[F⁻]³ = 2×10^−19 = S x (0.011+3.S)³

We work with: 2×10^−19 = S x (0.011+3.S)³, and we clear the "S"

=> S = 1.5x10^-13 mol/L x (195.9 g/mol) = 2.93x10^-11 g/L

The molar mass of LaF3 = 195.9 g/mol

Answer: S = 2.93x10^-11 g/L

Answer:

Explanation:

Here, we want to get the number of grams in 12.5 moles NaBr

To get this, we have to multiply the number of moles by the molar mass of NaBr

The molar mass of NaBr is 103 g/mol

Thus, we have the mass as:

This can be approximated to 1290 which is the nearest whole number

Answer:

D) 86.8%

Explanation:

It necessary to use the molar mass of Br (80g/mol) and MgBr2 (184g/mol). The MgBr2 is the 100%, so with a mathematical rule of three we can calculate the percent by mass of bromine.

In the molecule of MgBr2 there are 2 bromine, so the total mass of bromine it is 160g (80gx2):

Finally, the percent by mass of bromine is 86.9% (86.8%).

Givens.

• Lidocaine is available as a 2.0% (w/v) solution.

• The mass of solute is 60. mg of lidocaine.

To find the volume of this solution, we use the following equation.

Use the given magnitudes and solve for volume.

But, we need to use grams.

Therefore, the volume of this solution is 3.0 mL.

Let's see an illustration of a water molecule:

You can see that the oxygen has two pairs of electrons free representing a partial negative charge. These partial negative charges don't allow the molecule has a linear structure. All of the electron pairs—shared and unshared—repel each other and that's why the water molecule has a bent shape, because of these unshared electrons of oxygen.

Answer:

Hafnium is more likely to be the identity of the substance.

Explanation:

The given information about the substance is:

- Mass: 46.9g

- Volume: 3.5cm^3

- Solid at room temperature (23°C)

We can calculate the density of the substance by replacing the values of mass and volume in the density formula:

Now we know that the density of the substance is 13.4g/cm^3.

At this point, the substance could be mercury or hafnium, because they have a similar density, but we also know that the substance is solid at 23°C, so since hafnium has a melting point of 2,233°C, it is more likely to be the identity of the substance.,

To solve the question we will assume that the gas behaves like an ideal gas, that is to say, that there is no interaction between the molecules. Assuming ideal gas we can apply the following equation:

Where,

P is the pressure of the gas

V is the volume of the gas

n is the number of moles

R is a constant

T is the temperature

Now, we have two states, an initial state, and a final state. The conditions for each state will be.

Initial state (1)

P1=975Torr=1.28atm

V1=3.8L

T1=-18°C=255.15K

Final state(2), STP conditions

P2=1atm

T2=273.15K

V2=?

We will assume that the number of moles remains constant, so the nR term of the first equation will be constant. For each state, we will have:

Since nR is the same for both states, we can equate the equations and solve for V2:

We replace the known values:

At STP conditions the gas would occupy 5.2L. First option

Answer

Hydrogen and Oxygen

Explanation

During Light reactions of Photosynthesis, the chlorophyll will be activated by light. This light-activated chlorophyll will split the water molecule to release H+ ions and also oxygen. This process is called Photolysis.

Therefore, the correct option to your question is: Hydrogen and Oxygen

32.6 grams

Given the reaction between aluminium and ferric oxide as shown;

Determine the moles of Aluminium

Mole = Mass/Molar mass

Mole = 10.5/26.98

Mole of Al = 0.3892moles

According to stoichiometry, 2moles of aluminium produced 3 moles of Iron, the moles of Iron needed is given as:

moles of Fe = 3/2 * 0.3892

moles of Fe = 0.5838moles

Determine the mass of iron

Mass of Fe = moles * molar mass

Mass of Fe = 0.5838 * 55.845

Mass of Fe = 32.6grams

Hence mass of iron that can be produced from 10.5 grams of aluminium is 32.6 grams

Answer

b. Add solute to a saturated solution and heat until all of the solute dissolves. Then, slowly cool to the original temperature.

Explanation

A supersaturated solution contains more dissolved solute than required for preparing a saturated solution and can be prepared by heating a saturated solution, adding more solute, and then cooling it gently. Excess dissolved solute crystallizes by seeding supersaturated solution with a few crystals of the solute.

Therefore, a supersaturated solution is prepared by:

b. Add solute to a saturated solution and heat until all of the solute dissolves. Then, slowly cool to the original temperature.

Although there are neutral solutions that feel slipery, this is not a characteristic of all neutral solutions.

Acid solutions normally feels similar to neutral solutions, just wet.

However, base solutions has the characteristics of feeling slippery.

So, the most correct answer would be base

Answer: Bases

Explanation:

Bases have a slippery feel. Many soaps and detergents contain bases. Strong bases are able to react with the fatty acids and oils that naturally occur on the surface of your skin. The product of the reaction (which is known as saponification) is effectively a soap, which is why it feels slippery.

EXPLANATION:

PART

Soda drink is a mixture

PART B

Soda drink is a mixture and not a compound. This is because it contains different constituents and they are mixed together in the right proportion. Also, the composition of the constituents is uniform throughout the mixture.

1) Write the chemical equation.

List the elements in the reaction.

Reactants

C: 12

H: 24

O: 4

Products

C: 1

H: 2

O: 3

2) Balance C.

List the elements in the reaction.

Reactants

C: 12

H: 24

O: 4

Products

C: 12

H: 2

O: 25

3) Balance H.

List the elements in the reaction.

Reactants

C: 12

H: 24

O: 4

Products

C: 12

H: 24

O: 36

4) Balance O.

List the elements in the reaction.

Reactants

C: 12

H: 24

O: 36

Products

C: 12

H: 24

O: 36

5) Balanced chemical equation.

Step 1 - How to tell whether a given substance is ionic or covalent

To decide whether a substance is ionic or covalent, we must look for metals in its formula. If the substance is composed of both metals and non metals, it is an ionic susbtance.

If it's, on the other hand, composed solely by non-metals, it is a covalent substance.

Covalent substances do not produce ions in aqueous solution. Therefore, they can't be "broken into ions".

Step 2 - Analysing the given substances

H2O --> composed of H and O; both non-metals, so covalent

LiF --> composed of a metal (Li) and a non-metal (F), so ionic

K3PO4 --> composed of a metal (K) and non-metals (P, O), so ionic

AgCl --> composed of a metal (Ag) and non-metal (Cl), so ionic

Step 3 - Answering the exercise

All substances except H2O should be broken into ions when writing a complete ionic equation.

Answer: all except H2O

The ideal gas model was created to summarize some laws and study the behaviour of the gases, that depends on the properties.

It is really helpful and it is the first approach to the real behaviour of the gases, because all the other equations that came out after it, they have a basis on it. Historically, the ideal gas model was one of the first and most suitable ways to describe and calculate the properties of the gases.

It is also important that it's one of the easiest ways to relate the properties that are in the model, and it's very useful under certain conditions (specially temperature and pressure).

First, we have to convert the number of molecules to the number of moles of CO2 (carbon dioxide), and to do this we can do the Avogadro's number:

The Avogadro's number helps us to determine the number of moles based on the number of molecules or atoms of a compound. This number is 6.022 x 10 ^(23) /mol.

So, the conversion from molecules to moles would be:

Now, using this data we can calculate the number of moles needed for propane (C3H8).

In the chemical reaction, you can see that 1 mol of propane produces 3 moles of CO2, so the calculation would be:

The answer is that 0.78 moles of C3H8 were burned and produced 2.325 moles of CO2 which is 1.4 x 10 ^(24) molecules of CO2.

Step 1 - Understanding what is a biotic factor

Biotic, as well as other words with "bio" in them, is related to living organisms. A biotic factot is, therefore, a factor which depends on living organisms. When living organisms shape their environment, as well as other living beings environments, we call it a "biotic factor".

Step 2 - Using the definition to solve the exercise

a) Competition among predators: since this is a consequence of the struggling between two or more living beings, the outcome of it is surely a biotic factor. Individuals can die because they could not find enough food due to competition. A population could thus be modified by this biotic factor, for example.

b) A disease caused by bacteria: a bacteria is a living being and a disease can disastrously kill an entire population, radically changing the ecological relations and the environment. This is another biotic factor.

c) Invasive species: this is also caused by living beings. When a specie invades another species territory, there may be fight among them or just resources sharing. Either way, the ecological relations will be drastically modified. This accounts for a biotic effect as well.

d) weather: this is not solely caused by living beings. In fact, it depends rather poorly on living beings, and much more on Earth's temperature, geographical location an so on. Since the changes caused by weather are not from a living source, this is not a biotic factor.

The answer is thus item d.

Explanation:

The question requires us to identify the two elements present in the molecular formula C10H12O6N5P which present similar chemical and physical properties.

First, we need to identify all elements present in the molecule C10H12O6N5P:

- carbon (C)

- hydrogen (H)

- oxygen (O)

- nitrogen (N)

- phosporus (P)

Next, we can analyze the position of these elements in the periodic table:

Note that H is on the left side of the table, while the other elements (C, N, O and P) are closer together on the right side of the table.

We can see that although there are some elements close on the table, only N and P are part of the same group of the periodic table. Based on this, we can say that N and P should present similar properties because they are part of the same group.

Final answer: N and P should present similar chemical and physical properties (letter D).

Explanation:

Hey! The answer is True!

There are 1.02391×1024  no. of atoms in 1.70 moles of Calcium (Ca)

The approximate number of nucleons (protons or neutrons) in a gram of common stuff is known as the Avogadro number. 1 mole of any material contains the no of particles equal to the Avogadro number, that is, 6.023×1023particles.

The chemical element calcium has the atomic number 20 and the letter Ca as its symbol. Calcium is an alkaline earth metal that reacts with air to create a black oxide-nitride coating. Its heavier homologues barium and strontium are most similar to it in terms of physical and chemical characteristics.

Now,

Acc. to the Avogadro Number principal every 1 mole of any material contains the no of particles equal to the Avogadro number, that is, 6.023×1023particles.

So, the given amount of Calcium contains atom as follows:

1.70×6.023×1023 =1.02391×1024 atoms

Hence, There are 1.02391×1024  no. of atoms in 1.70 moles of Calcium (Ca)

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One carbon atom and one oxygen atom bound together by three bonds make up carbon monoxide. The number of molecules in 3.00 L of CO gas at STP is 67.2 liters.

Colorless, lethal, odorless, tasteless, and combustible, carbon monoxide is a gas that is somewhat less thick than air. One carbon atom and one oxygen atom bound together by three bonds make up carbon monoxide. The oxocarbon family's simplest molecule is this one.

Headache, dizziness, weakness, nausea, upset stomach, vomiting, chest discomfort, and confusion are the most typical signs of CO poisoning. The symptoms of CO are frequently compared to the flu. CO can cause you to lose consciousness or kill you if you breathe it in heavily.

If the gas is at STP,

Then 1 mole = 22.4 liters.

3 moles x 22.4 L/mol

= 67.2 liters.

Thus, The number of molecules in 3.00 L of CO gas at STP is 67.2 liters.

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To convert %Mass to Molarity, we have to know two things: the molecular mass of the solute and the density of the solution.

The first step is to convert the mass of the solute to moles using the molecular mass.

The second step is to conver the mass of the solution to liters of solution using the density.

Finally, the last step is to simplify the obtained result.

Given the following parameters

moles of C21H23NO5 = 3.4 moles

Since there are 23 atoms of hydrogen in the compound, hence the moles of hydrogen in the compound is given as:

According to the Avogadro's constant

Convert the moles of hydrogen to atoms

Answer:

2. Ionic because the difference is 2

3. Based on loss and gain of electrons

4. Share the electrons unequally.