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Answer:

Magnesium oxide is an ionic compound that can be used as a building material. MO2 is actually a raw material that used in producing cement for building houses, buildings, and other constructions.

Explanation:

Answer:

w/w means weight/weight

Therefore, in a 250 g of solution, 5% needs to be KCl,  

i.e. 5% x 250 = 12.5 g of KCl is needed.

The masses of KCl and H2O are needed to make 250 g of 5.00 % solution is 12.5 g of KCl and 237.50 g of H2O.

Since there is the solution of 250 g of 5.00 % solution

So, here

Mass of KCl is = 5% of 250 = 12.5 g

And, the mass of H2O is

= 250 - 12.5g

= 237.50 g

Hence, The masses of KCl and H2O are needed to make 250 g of 5.00 % solution is 12.5 g of KCl and 237.50 g of H2O.

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Answer:

Democritus

Explanation:

Answer:

Democritus

Explanation:

They called him that because of his cheerfulness and how he treated people .

Hoped I helped-

Sleepy-

The 12 stands for the number of electrons that fill the f orbital

In an atom there are levels of energy in the shell and sub shell  

This energy level is expressed in the form of electron configurations.  

Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is  

• s: 2 electrons  

• p: 6 electrons  

• d: 10 electrons and  

• f: 14 electrons  

4f¹² :

4 : number of shell

12 : the number of electrons that fill the f orbital

Answer:

1st one is...

Explanation:

The 1st one is change in size or shape. 2nd one is formation of precipitate. 3rd one is physical change. 4th one is formation of gas.

Answer:

4moles of carbon trihydride

Answer:

Average atomic mass of chlorine is 35.48 amu.

Explanation:

Given data:

Percent abundance of Cl-35 = 76%

Percent abundance of Cl-37 = 24%

Average atomic mass = ?

Solution:

Average atomic mass  = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (76×35)+(24×37) /100

Average atomic mass =  2660 + 888 / 100

Average atomic mass  = 3548/ 100

Average atomic mass = 35.48 amu

Average atomic mass of chlorine is 35.48 amu.

Answer:

Is it multiple choice or what I need to know the details

Explanation:

Answer:

Answer : The volume of water and alcohol present in 675 mL of this solution is 405 mL and 270 mL respectively.

Explanation: As we are given that 40.0 % (v/v) alcohol solution. That means, 40.0 mL of alcohol present in 100 mL of solution.

Now we have to calculable the volume of alcohol in 675 mL solution.

As 100 mL of solution contains 40.0 mL of alcohol

So, 675 mL of solution contains alcohol

Thus, the volume of alcohol = 270 mL

Now we have to calculate the volume of water.

The volume of water = Volume of the solution - Volume of alcohol

Volume of water = 675 mL - 270 mL

The volume of water = 405 mL

Thus, the volume of water = 405 mL

Hence, the volume of water and alcohol present in 675 mL of this solution is 405 mL and 270 mL respectively.

The 720mL of an 80-proof brandy which is 40.0% (v/v) ethyl alcohol, contains 288 mL of ethyl alcohol.

The Percent solutions can be expressed in the form of volume/volume percentage, weight/volume percentage, or, weight/weight percentage. The concentration of the solution in percentage is calculated as the fraction of the weight or volume of the solute related to the total weight or volume of the solution.

The solution where concentration requires to be represented in volume percent (v/v%) when the solute is a liquid phase. It is also applicable to the numerator and the denominator in volume units and is called volume/volume percent.

Volume percentage = (Volume of solute/volume of solution) x 100

The given brandy has ethyl alcohol the v/v % is 40 %.

It means the 40 ml of ethyl alcohol is present in the 100ml of brandy

Given the volume of brandy = 720 ml

Volume of ethyl alcohol in 720 ml of brandy = (40/100)×720 = 288 ml

Therefore, 288 ml of ethyl alcohol is present in 720 ml of brandy which is 40.0% (v/v) ethyl alcohol.

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Your question is incomplete, but most probably complete question was,

An 80 proof brandy is 40.0% (v/v) ethyl alcohol. The "proof" is twice the percent concentration of alcohol in the beverage. How many milliliters of alcohol are present in 720 mL of brandy?

Answer:

0.013 mole.

Explanation:

From the question given above, the following data were obtained:

Time (t) = 94.6 mins

Current (I) = 224.8 mA.

Mole of electrons (e) =?

Next, we shall convert 94.6 mins to seconds. This is illustrated below:

1 min = 60 s

Therefore,

94.6 mins = 94.6 min × 60 s / 1 min

94.6 mins = 5676 s

Thus, 94.6 mins is equivalent to 5676 s.

Next, we shall convert 224.8 mA to ampere (A). This can be obtained as follow:

1 mA = 1×10¯³ A

Therefore,

224.8 mA = 224.8 mA × 1×10¯³ A / 1 mA

224.8 mA = 0.2248 A

Thus, 224.8 mA is equivalent to 0.2248 A.

Next, we shall determine the quantity of electricity flowing in circuit. This can be obtained as follow:

Time (t) = 5676 s

Current (I) = 0.2248 A

Quantity of electricity (Q) =?

Q = it

Q = 0.2248 × 5676

Q = 1275.96 C

Finally, we shall determine the mole of electron by converting the quantity of electricity (i.e 1275.96 C) to number of electrons. This can be obtained as follow:

96500 C = 1 e

Therefore,

1275.96 C = 1275.96 C × 1 e / 96500 C

96500 C = 0.013 e

Thus, the mole of electron trasfered in the process is 0.013 mole.

Answer:

Explanation:

In carbon monoxide ,

2.5 g of carbon reacts with 3.33 g of oxygen

In unknown gas X ,

.75 g of carbon reacts with 2 .00 g of oxygen

2.5 g of carbon will react with 6.66 g of oxygen in X gas .

Ratio of oxygen in two compounds , reacting with same mass of carbon

= 3.33 : 6.66

= 1 : 2 , a simple ratio

It follows law of multiple proportions .

First gas is CO or carbon monoxide

X gas is CO₂ or carbon dioxide .

In this gas , ratio of oxygen reacting with same amount of carbon is doubled .

D. People with different goals can make contributions to scientific knowledge

Both Schwann and Virchow had different thoughts and ideas. Schwann wanted to understand how cells worked - Virchow wanted to know the origin of diseases. Different goals.

Answer:

D

Explanation:

I got it right on studyisland

Answer:

CaCO[tex]_{3s}[/tex]  →  CO[tex]_{2g}[/tex]   +   CaO[tex]_{s}[/tex]  

Explanation:

Given reactants:

 Omar heated small piece of calcium carbonate

Product;

  it gave off carbon dioxide gas and solid calcium oxide;

Problem,

Equation of the reaction;

Solution:

 Calcium carbonate →  Carbon dioxide + Calcium oxide

           CaCO[tex]_{3s}[/tex]  →  CO[tex]_{2g}[/tex]   +   CaO[tex]_{s}[/tex]  

Answer:

d. the relative proportions of the elements in the compound.

Explanation:

The chemical formula of a compound indicates the relative proportions of the element in the compound.

Answer:

6.711 × 10²⁴ molecules Mg(OH)₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

650.0 g Mg(OH)₂

Step 2: Define conversions

Avogadro's Number

Molar Mass of Mg - 24.31 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of Mg(OH)₂ - 24.31 + 2(16.00) + 2(1.01) = 58.33 g/mol

Step 3: Convert

[tex]650.0 \ g \ Mg(OH)_2(\frac{1 \ mol \ Mg(OH)_2}{58.33 \ g \ Mg(OH)_2} )(\frac{6.022 \cdot 10^{23} \ molecules \ Mg(OH)_2}{1 \ mol \ Mg(OH)_2} )[/tex]

= 6.71061 × 10²⁴ molecules Mg(OH)₂

Step 4: Check

We are given 4 sig figs. Follow sig fig rules.

6.71061 × 10²⁴ molecules Mg(OH)₂ ≈ 6.711 × 10²⁴ molecules Mg(OH)₂

Answer:

Element Symbol # of Atoms

Sodium   Na   2

Cobalt   Co   3

Hydrogen  H  20

Oxygen   O   10

Explanation:

The heat evolved with the [tex]\rm B_2H_6[/tex] has been 58.637 kJ.

From the balanced chemical equation, 1 mole of [tex]\rm B_2H_6[/tex] reacts with 2 moles of Chlorine to give 3 moles of boron chloride and 6 moles of HCl,

The chlorine has been required in double the quantity of boron hexahydride.

The moles of Chlorine has been the limiting reactant.

The chlorine that has been responsible for the reaction with [tex]\rm B_2H_6[/tex] will be:

6 Chlorine = 1 [tex]\rm B_2H_6[/tex]

5.65 L Chlorine = [tex]\rm \dfrac{5.65}{6}[/tex]

5.65 L Chlorine = 0.942 L [tex]\rm B_2H_6[/tex].

The moles of [tex]\rm B_2H_6[/tex] can be calculated as:

1 Mole = 22.4 L

Moles of [tex]\rm B_2H_6[/tex] in 0.942 L = 0.042 mol.

The heat evolved for 1 mole [tex]\rm B_2H_6[/tex] has been -1396 kJ.

The heat evolved for 0.042 mol [tex]\rm B_2H_6[/tex] = 0.042 × -1396 kJ.

The heat evolved = 58.637 kJ.

The heat evolved with the [tex]\rm B_2H_6[/tex] has been 58.637 kJ.

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Answer:

Physical change because it can go back to its original form.

Explanation:

Answer:

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Explanation:

Answer:

Dissolves in water: Acetone, 1-propanol, Methanol

Do not dissolve in water: Hexane, Decane

Explanation:

From the principle that like dissolves like,polar substances will dissolve in polar solutions, while non-polar substances will dissolve in non-polar substances.

Water is a polar solution, therefore, polar substances will dissolve in it.From the given options:

Acetone is a polar molecule, therefore, it will dissolve in water.

1-propanol is a polar molecule, therefore, it will dissolve in water.

Hexane is a non-polar molecule, therefore, it will not dissolve in water.

Methanol is a polar molecule, therefore, it will dissolve in water.

Decane is a non-polar molecule, therefore, it will not dissolve in water

Answer:

Climate change

Explanation:

Climate change is primarily a problem of too much carbon dioxide (CO2) in the atmosphere. This carbon overload is caused mainly when we burn fossil fuels like coal, oil and gas or cut down and burn forests

Answer:

4 m

Explanation:

Answer:

-1.94  * 10^-18 J

Since the electron moved from a higher to a lower energy level (n = 3 → n = 1) it is an emission.

Explanation:

From Rydberg equation;

E = -RH(1/n^2final - 1/n^2initial)

For a transition from  n = 3 → n = 1

RH = 2.18 * 10^-18 J

E = -(2.18 * 10^-18) (1/1^2 - (1/3^2)

E = -(2.18 * 10^-18) (1-1/9)

E= -(2.18 * 10^-18) (8/9)

E = -1.94  * 10^-18 J

Answer:

0.44L

Explanation:

Given parameters:

  Initial volume  = 0.75L

  Initial temperature  = 25°C  = 273 + 25 = 298K

  Final temperature  = -100°C  = 273 + (-100) = 173K

Unknown:

New volume of the balloon = ?

Solution:

According to Charles's law;

   "the volume of a fixed mass of a gas varies directly as its absolute temperature if the pressure is constant".

Mathematically;

    [tex]\frac{V_{1} }{T_{1} }[/tex]   =  [tex]\frac{V_{2} }{T_{2} }[/tex]  

  V and T are temperature values

  1 and 2 are the initial and final states

Insert the parameters and solve;

   [tex]\frac{0.75}{298}[/tex]   = [tex]\frac{V_{2} }{173}[/tex]  

    298V₂   = 129.75

           V₂  = 0.44L

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Answer:

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