plsss anwer my questions in the picture​

Answer:

2

Explanation:

4s2 has 2 valence electrons

Valence shell is the shell which is the outermost shell, that is filled in the last, before valence shell is penultimate shell. Therefore 2 valence electron are there in the valence shell.

Element generally consist of atoms or we can say atoms combine to form element. Atoms of an element is always same, means all the properties of all atoms of one type of element is same.

From our question the electronic configuration of element is given as

1s²2s²2p⁶3s²3p⁶4s²

Valence electron is the one which is present in the outermost shell or orbit. So, form above electronic configuration we can say that 4 is the outermost shell and in this shell 2 electron is present. Therefore 2 electron are there in the valence shell as valence electron.

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Answer:nuclear reaction

Explanation: Nuclear fusion is a type of nuclear reaction where two light nuclei collide together to form a single, heavier nucleus. Fusion results in a release of energy because the mass of the new nucleus is less than the sum of the original masses.

Fusion is the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy.

The enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ

The objective of this question is to determine the value of ΔH and ΔE of combustion is for 1 mole of methane.

If we look closely at the question, we will realize that at constant pressure, methane burns and produces heat of 804 kJ into the surroundings.

Since heat is released;

ΔH = -804 kJ

It also does a work of 3kJ, since work is done on the system

W = - 3kJ

According to the first law of thermodynamics;

ΔE = ΔH  -  W

ΔE = (-804 - (-3 )) kJ

ΔE = -801 kJ

Therefore, we can conclude that the in 1 mole of methane, the enthalpy ΔH of combustion is - 804 kJ. The change in internal energy ΔE of the reaction process is -801 kJ

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Hemoglobin with bound carbon dioxide and hydrogen ions is carried in the blood back to the lungs, where it releases the hydrogen ions and carbon dioxide and rebinds oxygen. Thus, hemoglobin helps to transport hydrogen ions and carbon dioxide in addition to transporting oxygen.

I hope you feel better soon! :)

Due to errors in volume and moles measurement by the student, the true value of the molar gas constant is less than the obtained value.

The Percent error is 1.39%

Percent error is defined as the ratio of error and true value of a measurement expressed as a percentage.

Error = |true value - measured value|

The error in the students measurement = |0.08206 - 0.0832|

Error = 0.00114

Percent error = (0.00114/0.08206) × 100%

Percent error = 1.39%

The formula to determine the molar gas constant R is given below:

[tex]R = \frac{PV}{nT}[/tex]

Since the student value is higher than the true value, the possible sources of error include:

Therefore, the true value of the molar gas constant is less than the obtained value.

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The molecules of the two gases will have the same kinetic energy at room temperature.

The average kinetic energy of gaseous molecules can be calculated using the formula:

Kinetic Energy = 3/2RT, where R = constant and T = temperature in Kelvin

This means that the kinetic energy of a gaseous molecule is dependent on the temperature of the molecule only.

In other words, the molecular mass of molecules of gases has no bearing on the kinetic energy of each molecule.

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Answer:

Bromine

Mercury

Bromine (symbol Br and atomic number 35) is a reddish-brown liquid, with a melting point of 265.9 K. Mercury (symbol Hg and atomic number 80) is a toxic shiny silvery metal, with a melting point of 234.32 K.

All of these properties are due to the chemical structure of the compound. The chemical structure includes the bonding angle, the type of bonds, the size of the molecule, and the interactions between molecules. Slight changes in the chemical structure can drastically affect the properties of the compound.

Answer:

B) Sterile droppers and petri dishes

Answer:

Ba 80.148%. H 1.77% O 18.657%

Answer:

Since water has a density of 1 gram per cubic centimeter, then the container would need to be 800 cubic centimeters. if this container were a perfect cube, then the length of the side of the container would be equal to the cube-root of 800, which is approximately 9.28 cm to a side, or 3.65 inches to aside.

Answer:

Westerlies are prevailing winds that blow from the west at midlatitudes. They are fed by polar easterlies and winds from the high-pressure horse latitudes, which sandwich them on either side.Nov 15, C answer

Tap water is a mixture not compound due to presence of many substance.

Tap water is an example of mixture not compound because in tap water, water is not available in pure form, it has many substances mix with water and those substances make no bond with water.

It has dissolved compounds like calcium carbonate, magnesium and fluoride. Different elements or compounds are physically combined rather than chemically linked together so we can conclude that student A is correct that tap water is a mixture.

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Answer:

ok

Explanation:

Explanation:

since diferentes colours of light través at diferentes speeds, the refractiva index is diferentes for each color. The result? that whenthe White light países thought the prism it cover into a red light

The role played by hydraulic fluid in a hydraulic machine is as a medium for

the transfer of force.

Hydraulic fluid is used primarily in a hydraulic machine for the transfer of

force from one point to another. This makes the system able to perform the

required functions.

Hydraulic fluid also has other functions such as being a coolant and as a

cleaning agent(removal of contaminants) which aren't its major function.

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measurement is the process of finding the value of any Unknown physical quantities in standard value.

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Measurement has been defined as the concept widely used in math and science to quantify an object. It is used to denote the quantification of the event or the object with respect to other or individually.

Hence, the definition of measurement is the process of determining the size or smallness of a physical amount by comparing it to a reference quantity of the same kind as the object.

It has been used to determine the quantity to be small or large based on some predetermined standard or values. It compares the physical quantity like mass can be estimated using kilograms or grams.

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The molarity of the Ca(NO3)2 solution would be 0.005 M

First, let us look at the balanced equation of the reaction:

[tex]2HNO_3+Ca(OH)_2 ---> Ca(NO_3)_2+2H_2O[/tex]

The mole ratio of HNO3 to Ca(OH)2 is 2:1.

Mole of HNO3 = molarity x volume

                            = 0.2 x 150/1000

                              = 0.03 mole

Mole of Ca(OH)2 = 0.01 x 150/1000

                             = 0.0015

Thus, there is no limiting or excess reactant.

Also from the equation, mole ratio of Ca(OH)2 to Ca(NO3)2 is 1:1. Hence, the mole of Ca(NO3)2 would also be 0.0015 mole.

The total volume of the resulting solution would be: 150 +150 = 300 mL

Thus, the molarity of the resulting Ca(NO3)2 would be:

Molarity = mole/volume

              = 0.0015/0.3

               = 0.005 M

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Answer:

Aluminium ions present's in 65.5mL of 0.210

M All 3solution is Given below-:

Answer and Explanation: 1

The first step is to determine the moles of aluminum ions. This utilizes the volume, molar concentration, and subscripts from the chemical formula of aluminum (III) fluoride as shown.

65.5 mL×1 L1000 mL×0.210 mol AlF31 L×1 mol Al3+1 mol AlF3=0.013755 mol Al3+65.5 mL×1 L1000 mL×0.210 mol AlF31 L×1 mol Al3+1 mol AlF3=0.013755 mol Al3+

To calculate for the number of aluminum ions, we use Avogadro's number as shown.

0.013755 mol Al3+×6.022×1023 ions1 mol Al3+=8.28×1021 ions Al3+.

Itz the ans. of collage ok man.

Answer:

m0.013755

m

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A

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3

+

×

6.022

×

10

23

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1

m

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A

l

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+

=

8.28

×

10

21

i

o

n

s

A

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3

+

L

×

1

L

1000

m

L

×

0.210

m

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l

A

l

F

3

1

L

×

1

m

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l

A

l

3

+

1

Explanation:

The first step is to determine the moles of aluminum ions. This utilizes the volume, molar concentration, and subscripts from the chemical formula of aluminum (III) fluoride as shown.

65.5. To calculate for the number of aluminum ions, we use Avogadro's number as shown.

Answer:

CH4(g)+2O2(g)→CO2(g)+2H2O(g)

Explanation:

For a complete combustion reaction of a hydrocarbon, oxygen is always one of the reactants, and the products are always carbon dioxide and water.

Answer:

77%

Explanation:

The formula for finding percent change is change/original.

So, you have to do 0.3/0.39

You have to divide this to get 0.769 which can be rounded 0.77

0.77 as a percentage is 77%

So, the percentage mass increase of the carrot is 77%

Explanation:

May kwento po ba yan o yan na talaga

Answer:

6.02 × 1023

The molar mass from the periodic table is 32.00 g O2 = 1 mol O2, and by definition, 1 mol O2 = 6.02 × 1023 molecules O2.