4. DBearded waste of Co-60 must be stored until it is no longer radioactive. Cobalt-60
waste weighing 14.5g has been in storage før 26.5 years. How much of this radioisotope
was present when the sample was put in storage?

Answer:

C

Explanation:

The Law of Conservation of Mass states that matter cannot be created or destroyed and must be conserved. I is stating matter cannot be created, which is true. II is saying that matter can only be rearranged/conserved, which again is true. III states matter cannot be destroyed, which is also true. IV is incorrect because it doesn't make sense. Matter does matter.

Answer:

Gravity always pulls objects such as a desk, book or person down. Thus, when you jump gravity causes you to land on the ground. Friction, however, doesn't pull objects down

Answer:

1

Explanation:

Answer:

the answer is C

Explanation:

it can form 3 bonds

Answer: A. Gamma radiation can pass through your body

Explanation:

Let's use the Process of Elimination for this problem.

We will start off with B. Gamma radiation is always dangerous to the body.

Facts: Gamma radiation are not always dangerous to the body. Most of the time, Gamma rays and radiation will go through with little to no effect at all. So, now we know that the answer can not be B. Gamma radiation is always dangerous to the body.

Next, let's check if C. Gamma radiation is produced when a neutron turns into a proton is true.

Facts: Gamma radiation has nothing to do with neutrons turning into protons and protons turning into neutrons. Gamma rays are a type of radiation that is everywhere. Gamma rays do not make neutrons into protons. Now, we will eliminate option C. Gamma radiation is produced when a neutron turns into a proton.

Let's check if D. Gamma radiation cannot go through surfaces rather, it will beures  off them is true or not is true or not.

Facts: Gamma rays can enter your body, they do not just bounce off of your body. Gamma rays are invisible and have no weight. They are like lasers and they can enter your body. Now, we know the answer should not be D. Gamma radiation cannot go through surfaces rather, it will beures  off them is not a true statement.

Finally, let's check if A. Gamma radiation can pass through your body is true or not.

Facts: Gamma rays can pass through your body because it is like a natural laser. They can also cause ionizations that can damage tissue in your body. But most of the time, the damage to your tissue is minor. So, we know A. Gamma radiation can pass through your body is a true statement.

Feel free to comment if u dont understand it :)

According to the concept of Avogadro's number , there are 4.48 moles in 2.70 X 10 ²⁴ atoms of copper.

Avogadro's number is defined as a proportionality factor which relates number of constituent particles with the amount of substance which is present in the sample.

It has a SI unit of reciprocal mole whose numeric value is expressed in reciprocal mole which is a dimensionless number and is called as Avogadro's constant.It relates the volume of a substance with it's average volume occupied by one of it's particles .

According to the definitions, Avogadro's number depend on determined value of mass of one atom of those elements.It bridges the gap between macroscopic and microscopic world by relating amount of substance with number of particles.

Number of atoms can be calculated using Avogadro's number as follows: mass/molar mass×Avogadro's number

To obtain number of moles divide number of atoms by Avogadro's number that is  2.70 X 10 ²⁴ /6.023×10²³=4.48 moles .

Thus, there are 4.48 moles in 2.70 X 10 ²⁴ atoms of copper.

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Answer:

boron

Explanation:

Boron and aluminum lie in same group in modern periodic table and both have three valence electrons

Explanation:

The nucleus of an atom is surround by electrons that occupy shells, or orbitals of varying energy levels. The ground state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron. There is also a maximum energy that each electron can have and still be part of its atom.

Answer:

The answer is: Because solids are the most sense.

Option (b) is the correct answer.

Explanation:

The distance between molecules in solids r very small.Because they are so close, they can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighbor. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids.It is true that sound travels faster in solids. This is because in solid substances, molecules are much closer to each other due to which transfer of energy is much faster.

On the other hand, molecules in a liquid and gas are farther apart from each other due to which there will be less transfer of energy. As a result, sound does not travel quickly through liquids and gases.

Thus, we can conclude that sound travels most quickly through solids because the molecules in solids are very close together.

Answer:

yea, what they said.

Explanation:

Answer:

63 moles of carbon atoms, 115.5 moles of hydrogen atoms, and 57.75 moles of oxygen atoms i believe :)

Answer:

Q = 5671.05 J

Explanation:

Given data:

Mass of metal = 525 g

Initial temperature = 32.0 °C

Fina temperature = 43.0 °C

Heat absorbed by metal = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

specific heat capacity of metal X = 0.982 J/g.°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 43.00°C - 32.00°C

ΔT = 11.00°C

Q = 525 g × 0.982 J/g.°C  × 11.00°C

Q = 5671.05 J

Answer:

Ketone molecule

Explanation:

The type of molecule shown above is ketone molecule.

A molecule is a group of two or more atoms that are chemically combine together or are tightly held together by attractive forces.

Hence, we can conclude that option D is the answer.

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Answer:

Sorry how no this equation guys

Answer:

2.5.2 Atomistic Configurations of Oxygen in Silicon Crystals

Oxygen atoms are incorporated in the silicon lattice on an interstitial position (denoted by Oi), where the oxygen atom sits in an almost bond-centered position between two adjacent Si atoms [101]. Several of the local vibration modes are infrared (IR) active. The predominant IR line at 1104/cm (at room temperature) was calibrated with respect to other analytical methods, such as gas fusion and several radioactive techniques, and is used as the standard method for the quantitative determination of the oxygen content in as-grown silicon crystals (as-grown silicon usually contains only a negligible amount of precipitated oxygen).

Explanation:

Hope it will help):)

Answer:

an acid is any hydrogen containing substance that. can donate protons.

a base is a molocule that is able to accept hydrogen ion from an acid

a) ionic

chlorine is present in top of group 17 and right of period 3 and

electronegativity(the tendency to gain electrons)

increases up the group and right the group.

so it has high tendency to form anion.

In the same way both Na and K are present up the group and left side and the tendency to lose electrons in both becomes high and they tend to form cation.

Answer:

Answers with detail given below.

Explanation:

1) NaBr + KF    →       NaF  + BrK

Double replacement:

It is the reaction in which two compound exchange their ions and form new compounds.

AB + CD → AD +CB

2)   2Cu + MnCl₂       →      2CuCl + Mn

Single replacement:

It is the reaction in which one elements replace the other element in compound.

AB + C → AC + B

3) CO₂     →    O₂  + C

Decomposition reaction:

It is the reaction in which one reactant is break down into two or more product.

AB → A + B

4) C + 2H₂      →    CH₄

Combination reaction:

It is the reaction in which two or more simple substance react to give one or more complex product.

Answer:

285g of fluorine

Explanation:

To solve this problem we need to find the mass of Freon in grams. Then, with its molar mass we can find moles of freon and, as 1 mole of Freon, CCl₂F₂, contains 2 moles of fluorine, we can find moles of fluorine and its mass:

Mass Freon:

2.00lbs * (454g / 1lb) = 908g of Freon

Moles freon -Molar mass: 120.91g/mol- and moles of fluorine:

908g of Freon * (1mol / 120.91g) =

7.5 moles of freon * (2moles Fluorine / mole Freon): 15 moles of fluorine

Mass fluorine -Atomic mass: 19g/mol-:

15 moles F * (19g / mol) =

Answer:

V₂ = 1.86 L

Explanation:

Given data:

Initial volume = 4.30 L

Initial pressure = 1 atm

Initial temperature = 273.15 K

Final temperature = 302 K

Final volume =  ?

Final pressure = 2.56 atm

Solution:

According to general gas equation:

P₁V₁/T₁ = P₂V₂/T₂

V₂ = P₁V₁T₂ /T₁ P₂

V₂ = 1 atm ×4.30 L × 302 K / 273.15 K × 2.56 atm

V₂ = 1298.6 atm.L.K / 699.26 K.atm

V₂ = 1.86 L

Answer:

Mass of hydrogen produced  = 2.1 g

Mass of excess reactant left = 25.2 g

Explanation:

Given data:

Mass of Mg = 50.0 g

Mass of HCl = 75.0 g

Mass of hydrogen produced = ?

Mass of excess reactant left = ?

Solution:

Chemical equation:

Mg + 2HCl      →       MgCl₂ + H₂

Number of moles of Mg:

Number of moles = mass/molar mass

Number of moles = 50 g/ 24 g/mol

Number of moles = 2.1 mol

Number of moles of HCl:

Number of moles = mass/molar mass

Number of moles = 75 g/ 36.5 g/mol

Number of moles = 2.1 mol

now we will compare the moles of hydrogen gas with both reactant.

                     Mg       :        H₂

                       1          :       1

                     2.1         :     2.1

                   HCl         :        H₂

                      2          :          1

                    2.1          :        1/2×2.1 = 1.05 mol

HCl is limiting reactant and will limit the yield of hydrogen gas.

Mass of hydrogen:

Mass = number of moles × molar mass

Mass=  1.05 mol ×2 g/mol

Mass = 2.1 g

Mg is present in excess.

Mass of Mg left:

         HCl            :           Mg

             2             :            1

            2.1            :         1/2×2.1 = 1.05

Out of 2.1 moles of Mg 1.05 react with HCl.

Moles of Mg left = 2.1 mol - 1.05 mol = 1.05 mol

Mass of Mg left:

Mass = number of moles × molar mass

Mass = 1.05 mol × 24 g/mol

Mass = 25.2 g

Answer:

They use the pH scale

Explanation:

The strong acid and strong base has high rate constant of dissociation. Weak acid and base are the one whose rate constant for the dissociation is low, they do not dissociate readily in water. Scientist use pH scale to classify substances that are either an acid or a base.

Acid is a solution which releases H⁺ hydrogen ion when dissolved in water. Base are the solution which releases hydroxide ion OH⁻ ion when dissolved in water. . At room temperature pH scale is between 0 to 14. pH of neutral solution is 7.

The pH of acid is between 0-7 on pH scale. acid turns blue litmus paper to red. Acids have sour taste and corrosive nature. Mathematically the concentration of hydrogen ion can be calculated using this formula

Mathematically,

pH=-log[H⁺]

Therefore, scientist use pH scale to classify substances that are either an acid or a base.

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Answer:

1. chemical fertillizers encourage plant disease

2. chemical fertillizers affect micro-organism living in the soil.

Explanation:

Answer:

Explanation:

When you are pedaling the bike, it is transforming chemical energy, supplied by the breakdown of the food you eat (any food), into mechanical energy to turn the pedals (energy we produce). The chemical energy is potential and the mechanical energy is kinetic.

Hope this helps :)

Answer:This pressure is transmitted throughout the liquid and makes it more difficult for bubbles to form and for boiling to take place. If the pressure is reduced, the liquid requires less energy to change to a gaseous phase, and boiling occurs at a lower temperature

Explanation:

Atmospheric Pressure and Boiling

The pressure of gas above a liquid affects the boiling point. ... If the pressure is reduced, the liquid requires less energy to change to a gaseous phase, and boiling occurs at a lower temperature

a. 627.1 m/s

b.  the rate of effusion of ethane = 1.7 faster than hexane

Given

T = 200 + 273 = 473 K

Required

a. the gas speed

b. The rate of effusion comparison

Solution

a.

Average velocities of gases can be expressed as root-mean-square averages. (V rms)  

[tex]\large {\boxed {\bold {v_ {rms} = \sqrt {\dfrac {3RT} {Mm}}}}[/tex]

R = gas constant, T = temperature, Mm = molar mass of the gas particles  

From the question  

R = 8,314 J / mol K  

T = temperature  

Mm = molar mass, kg / mol  

Molar mass of Ethane = 30 g/mol = 0.03 kg/mol

[tex]\tt v=\sqrt{\dfrac{3\times 8.314\times 473}{30} }=627.1~m/s[/tex]

b. the effusion rates of two gases = the square root of the inverse of their molar masses:  

[tex]\rm \dfrac{r_1}{r_2}=\sqrt{\dfrac{M_2}{M_1} }[/tex]

M₁ = molar mass ethane =30

M₂ =  molar mass hexane = 86

[tex]\tt \dfrac{r_1}{r_2}=\sqrt{\dfrac{86}{30} }=1.7[/tex]

the rate of effusion of ethane = 1.7 faster than hexane

Answer:

water, work

Explanation:

The flow of electros through a conductor is electric current. These electrons cannot be seen and so electric circuits can be used to model the arrangement and understand the process. Water flowing through pipes is a fitting mechanism that looks like the electrical circuit.

In this mechanism, the pipe is seen as the wire in the electric circuit while the pump is viewed as the battery. The pressure, like the voltage generated by the battery, comes from the pump and drives the water through the pipe.

Answer:

2.27%

Explanation:

The observed value of the boiling point = 71.8°C

The actual value of the boiling point = 70.2°C

We need to find the percentage error of the student's measurement. The percentage error in any value is given by :

[tex]\%=\dfrac{\text{calculated value-actual value}}{\text{actual value}}\times 100\\\\=\dfrac{71.8-70.2}{70.2}\times 100\\\\=2.27\%[/tex]

So, the required percentage error is 2.27%.