What is the total mass of Kr-42 remaining in a 20-mg sample after 48.8 hours?
(1) 2.5 mg
(2) 5.0 mg
(3) 10 mg
4) 20 mg​

Answer: 7

Explanation: i don't know how the HECK. -3-(-8)-(-2)=7 but I searched it up soooooo also I got it right

Answer:

THE FREEZING POINT OF A WATER SOLUTION OF FRUCTOSE MADE BY DISSOLVING 92 g OF FRUCTOSE IN 202g OF WATER IS -4.70 ◦C

Explanation:

To calculate the freezing point of a water solution of fructose,

1. calculate the molar mass of Fructose

( 12 * 6 + 1*12 + 16*6) =72 + 12 +96 = 180 g/mol

2. calculate the number of moles of fructose in the solution

number of moles = mass / molar mass

n = 92 g / 180 g/mol

n = 0.511 moles.

3. calculate the molarity of the solution

molarity = moles / mass of water in kg

molarity = 0.5111 / 202 g /1000 g

molarity = 0.5111 / 0.202

molarity = 2.529 M

4. calculate the change in the freezing point of pure solvent and solution ΔTf

ΔTf = Kf * molarity of the solute

Kf = 1.86 ◦C/m for water

ΔTf = 1.86 * 2.529

ΔTf = 4.70 C

5. the freezing point is therefore

0.00 ◦C - 4.70 ◦C = -4.70 ◦C

Answer:

-4.7°C

Explanation:

In this question, we want to calculate the freezing point of the water solution of fructose.

We proceed as follows;

Firstly, we find the number of moles of the fructose using molar mass

Number of moles = mass/molar mass

mass is 92g , molar mass of fructose is 180g/mol

Number of moles = 92/180 = 0.51 moles

Next thing is to calculate the molality of the solution = number of moles of fructose/mass of water in kg = 0.51/(202/1000) = 0.51/0.202 = 2.525m

Now, we calculate the freezing point depression;

Δ[tex]T_{f}[/tex] = [tex]K_{f}[/tex] × m

where [tex]K_{f}[/tex] refers to the molal freezing point depression of the solvent = 1.86

Δ[tex]T_{f}[/tex] = 1.86 × 2.525 = 4.7 °C

Since the presence of impurities decrease freezing point and the normal freezing point of water is 0 °C, the freezing point of the solution is 0-4.7 = -4.7 °C

Answer:

Mass and charge is conserved

Explanation:

According to the law of conservation of mass, matter is neither created or destroyed. With the exception of nuclear reactions where mass is converted to energy thereby leading to an apparent loss in mass, this law applies to chemical reactions.

A redox reaction is a type of chemical reaction which involves a transfer of electrons. In a redox reaction, the mass of reactant particles is conserved. Also, as electrons are transferred between atoms, one donates and the other accepts. The charge of atoms depends on this gain or loss of electrons. A gain of electrons reduced the charge of an atom whereas a loss of electrons increases the charge. This two processes occur concurrently, therefore, charge is also conserved.

Answer:

I’ll help what’s the question

Explanation:

Answer:

Aight wats da question

Explanation:

Answer:

A)

B) They are all compound substances

Explanation:

The salad and the glass of water with oil have two phases because their elements do not mix, we can see them separately. In the case of coffee with milk, there is only one phase because we can not see all the components separately, they are mixed in the solution.

They are all compound substances due to the fact that they are made of more than one element.

Answer: The molarity is 0.25 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in ml

moles of [tex]CO_2[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{11g}{44g/mol}=0.25mol[/tex]

Now put all the given values in the formula of molality, we get

[tex]Molarity=\frac{0.25\times 1000}{1000ml}[/tex]

[tex]Molarity=0.25M[/tex]

Therefore, the molarity is 0.25 M

Answer:

B. The molecules collide less frequently.

Explanation:

When the pressure of a gas is lowered, the molecules collide less frequently and the correct option is option B.

Pressure of a gas is a measure of the force exerted by gas molecules on the walls of the container in which the gas is contained. It is a result of the random and continuous collisions of gas molecules with the container surface.

When the pressure of a gas is lowered, it means that the force exerted by the gas molecules on the container walls decreases. This can occur due to a decrease in the number of gas molecules or a decrease in their average kinetic energy, resulting in less frequent and less forceful collisions with the container.

Lowering the pressure of a gas does not necessarily imply an increase in the number of gas molecules or a decrease in their volume.

Thus, the ideal selection is option B.

Learn more about Pressure of gas, here:

https://brainly.com/question/31525061

#SPJ6

Answer:

the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.

Explanation:

if you need a definition of a word, you can look in a dictionary as well for future reference

Answer:

Temperature means the hotness or coldness of anything.

Explanation:

The exact definition is: "The degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch."

Answer: C

Explanation:

For this problem, we would use Charles's Law. We fill in what we are given and solve.

Charles's Law: [tex]\frac{V_{1} }{T_{1} } =\frac{V_{2} }{T_{2} }[/tex]

[tex]\frac{10 L}{5K} =\frac{4.00L}{T_{2} }[/tex]

[tex]10T_{2}= 20[/tex]

[tex]T_{2}=2K[/tex]

Answer:

Electrolytes are salts or molecules that ionize completely in solution. As a result, electrolyte solutions readily conduct electricity.

Nonelectrolytes do not dissociate into ions in solution; nonelectrolyte solutions do not, therefore, conduct electricity.

nonelectrolyteA substance that does not dissociate into ions when in solution.

solutionA homogeneous mixture, which may be a liquid, gas, or solid, formed by dissolving one or more substances.

solute Any substance that is dissolved in a liquid solvent to create a solution.

electrolyte A substance that dissociates into ions when in solution.

saltAn ionic compound composed of cations and anions that are held together by electrostatic attraction.

when an ionizable solute dissociates, the resulting solution can conduct electricity. Therefore, compounds that readily form ions in solution are known as strong electrolytes. (By this reasoning, all strong acids and strong bases are strong electrolytes.)

By contrast, if a compound dissociates to a small extent, the solution will be a weak conductor of electricity; a compound that only dissociates weakly, therefore, is known as a weak electrolyte.

A strong electrolyte will completely dissociate into its component ions in solution; a weak electrolyte, on the other hand, will remain mostly undissociated in solution. An example of a weak electrolyte is acetic acid, which is also a weak acid.

Nonelectrolytes are compounds that do not ionize at all in solution.

Answer:It is upthrust...

Explanation:I don't say u must have to mark my ans as brainliest but if it has really helped u plz don't forget to thank me my friend....

Answer:

C6H120

Explanation:

atom ratio= 1:2:1 even though it has 6 carbon.

mass ratio=6:1:8

is this what you wanted/needed?

Answer:

B

Explanation:

energy needed to get a reaction started

hope this helps. good luck :)

Answer:

THE NEW VOLUME AT 1 K IS 1.2 L

Explanation:

Using Charles' law which states that the volume of a given gas is directly proportional to its temperature provided the pressure remains constant.

Mathematically written as;

V1/T1 = V2/T2   at constant pressure

V1 = Initial volume = 6L

T1 = initial temperature = 5K

T2 = Final temperature = 1K

V2 = final volume = unknown

Re-arranging the equation by making V2 the subject of the equation, we obtain;

V2 = V1 T2 / T1

V2 = 6 * 1 / 5

V2 = 1.2 L

The new volume of the gas sample at 1 K is 1,2 L

Answer:1.2 L

Explanation: according to Charles law, the volume of a fixed mass of gas is directly proportional to it's temperature.

Volume is the size of the space that a gas occupies and it can be measured in liters, cubic meters, cubic decimeters etc.

The solution to this question is in the attached photo

Answer:

2 moles of sugar in 1,000g of water

Answer:

B. 1, 1, 2

General Formulas and Concepts:

Chemistry - Reactions

Explanation:

Step 1: Define

RxN:   C₄H₆O₃ + H₂O → C₂H₄O₂

Step 2: Balance

C₄H₆O₃ + H₂O → 2C₂H₄O₂

We see that we have balanced everything at this point.

Answer:

36g of H2O.

Explanation:

We'll begin by writing the balanced equation for the reaction:

2NaOH + H2SO4 —> Na2SO4 + 2H2O

Next, we shall determine the mass of NaOH that reacted and the mass of H2O produced from the balanced equation. This is illustrated below:

Molar mass of NaOH = 23 + 16 + 1 = 40g/mol

Mass of NaOH from the balanced equation = 2 x 40 = 80g

Molar mass of H2O = (2x1) + 16 = 18g/mol

Mass of H2O from the balanced equation = 2 x 18 = 36g.

From the balanced equation above, we can see evidently that:

80g of NaOH reacted to produce 36g of H2O.

Answer:

Pressure

Explanation:

Basically when you are pressing something you are applying force over an area thus Pressure is force divided by area.

Answer:

pressure

Explanation:

Answer:

B. Beryllium

Explanation:

because the  trend of ionization is going up a group it increases, as going across a period it deceases. beryllium being closes to the hist point in the periodic table it has the highest ionization energy. hope this helps.  

Answer: B. Beryllium

Explanation: Apex

Answer:

lpg and oxygen are two gases which are supplied in compressed form in homes and hospitals

Explanation:

Answer : The correct option is, (C) 3

Explanation :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, [tex]CH_3Cl[/tex]

As we know that carbon has '4' valence electrons, hydrogen has '1' valence electron and chlorine has '7' valence electrons.

Therefore, the total number of valence electrons in [tex]CH_3Cl[/tex] = 4 + 3(1) + 7 = 14

According to Lewis-dot structure, there are 8 number of bonding electrons and 6 number of non-bonding electrons.

Hence, the number of lone pairs of electrons present on chlorine are, 3.

Answer:

The combustion will release -3,321 KJ/mol of energy

Explanation:

What we need to do here is to first calculate the number of moles of methane burnt.

Mathematically, the number of moles of methane burnt = mass of methane/molar mass of methane

Molar mass of methane = 16g /mol

Thus the

number of moles will be ;

59.7/16 = 3.73 moles

Now, 1 mole of methane produces -890 KJ/mol if energy

Then the energy produced by by 3.73 moles of methane would be 3.73 * 890 = -3,320.8125

which is approximately -3,321 KJ/mol

Kindly note that the amount of heat is negative because it is an exothermic reaction

Answer:

Option A. 1.02g of Fe.

Explanation:

Step 1:

The balanced equation for the reaction.

3Mg + Fe2(SO4)3 —> 3MgSO4 + 2Fe

Step 2:

Determination of the mass Fe2(SO4)3 that reacted and the mass of Fe produced from the balanced equation. This is illustrated below:

Molar Mass of of Fe2(SO4)3 = (2x56) + 3[32 + (16x4)] = 112 + 3[32 + 64] = 112 + 3[96] = 400g/mol

Mass of Fe2(SO4)3 from the balanced equation = 1 x 400 = 400g

Molar Mass of Fe = 56g/mol

Mass of Fe from the balanced equation = 2 x 56 = 112g

From the balanced equation above,

400g of Fe2(SO4)3 reacted to produce 112g Fe.

Step 3:

Determination of the mass of Fe produced by reacting 3.65g of Fe2(SO4)3.

This is illustrated below:

From the balanced equation above,

400g of Fe2(SO4)3 reacted to produce 112g Fe.

Therefore, 3.65g of Fe2(SO4)3 will react to produce = (3.65 x 112)/400 = 1.02g of Fe.

Therefore, 1.02g of Fe is produced from 3.65g of Fe2(SO4)3.

Answer:

[tex]V_{solution}=0.925L=925mL[/tex]

Explanation:

Hello,

In this case, we should define what molarity is, being the ratio between the moles of the solute and the volume of the solution in litres:

[tex]M=\frac{n_{solute}}{V_{solution}}[/tex]

Thus, the first step is to compute the moles of potassium nitrate, whose molar mass is 101.1 g/mol as shown below:

[tex]n_{solute}=374g*\frac{1mol}{101.1g} =3.70molKNO_3[/tex]

Next, as we are asked for the volume of the solution we simply solve for it:

[tex]V_{solution}=\frac{n_{solute}}{M}=\frac{3.70mol}{4.0mol/L} \\\\V_{solution}=0.925L=925mL[/tex]

Regards.

Answer:

0.93L

Explanation:

The following data were obtained from the question:

Molarity = 4M

Mass of KNO3 = 374g

Volume =..?

We'll begin by calculating the number of mole in 374g of KNO3. This is illustrated below:

Mass of KNO3 = 374g

Molar mass of KNO3 = 39 + 14 + (16x3) = 101g

Number of mole of KNO3 =..?

Number of mole = Mass/Molar Mass

Number of mole of KNO3 = 374/101 = 3.70 moles.

Now, we can obtain the volume of the solution as follow:

Molarity = mole /Volume

Volume = mole /Molarity

Volume = 3.70/4

Volume = 0.93L

Therefore, the volume of the solution is 0.93L