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Alex
2 years ago
6

Q22.  Which best represents how electrons are arranged in the energy levels of a carbon atom? A.First energy level = 1 electron

  Second energy level = 5 electrons b. First energy level = 3 electrons   Second energy level = 3 electrons C.First energy level = 2 electrons    Second energy level = 4 electrons D. First energy level = 4 electrons   Second energy level = 2 electrons
I know the answer is b but why?
Chemistry
1 answer:
Sati [7]2 years ago
5 0
The correct answer is C
the first energy level can hold up to 2 electrons, the second level can hold up to 8 electrons, the third level holds up to 18 electrons, etc.
For a regular element, the number of protons and electrons will be equal.  Carbon has 6 protons (same as the atomic number), so you need to start at the first shell (closest to the nucleus) and start filling.  The first level can only hold 2 electrons, so that means there are 4 left that will fit into the second level.
I hope this helps a little, I know it's confusing.  

You might be interested in
What is the driving force in the wittig reaction?
jonny [76]
Formation of strong phosphorous-oxygen bonds drives the Wittig reaction. Phosphorous is extremely oxophilic, meaning that it forms strong bonds with oxygen.
7 0
2 years ago
Calculate ΔH and ΔStot when two copper blocks, each of mass 10.0 kg, one at 100°C and the other at 0°C, are placed in contact in
ira [324]

Explanation:

The given data is as follows.

        m = 10.0 kg = 10,000 g    (as 1 kg = 1000 g)

      Initial temp. of block 1, T_{1} = 100^{o}C = (100 + 273) K = 373 K  

      Initial temp. of block 2, T_{2} = 0^{o}C = (0 + 273) K = 273 K

So, heat released by block 1 = heat gained by block 2

            mC \Delta T = mC \times \Delta T

  10000 g \times 0.385 \times (T_{f} - 100)^{o}C = 10000 g \times 0.385 \times (0 - T_{f})^{o}C

                  T_{f} - 100^{o}C = 0^{o}C - T_{f}    

                   2T_{f} = 100^{o}C

                          T_{f} = 50^{o}C

Convert temperature into kelvin as (50 + 273) K = 323 K.              

Also, we know that the relation between enthalpy and temperature change is as follows.

             \Delta H = mC \Delta T

                         = 10000 g \times 0.385 J/K g \times 323 K

                         = 1243550 J

or,                     = 1243.5 kJ

Now, calculate entropy change for block 1 as follows.

     \Delta S_{1} = mC ln \frac{T_{f}}{T_{i}}

            = 10000 g \times 0.385 J/K g \times ln \frac{323}{373}

            = 10000 g \times 0.385 J/K g \times -0.143

            = -554.12 J/K

Now, entropy change for block 2 is as follows.

   \Delta S_{2} = mC ln \frac{T_{f}}{T_{i}}

           = 10000 g \times 0.385 J/K g \times ln \frac{323}{273}

           = 10000 g \times 0.385 J/K g \times 0.168

           = 647.49 J/K

Hence, total entropy will be sum of entropy change of both the blocks.

            \Delta S_{total} = \Delta S_{1} + \Delta S_{2}

                       = -554.12 J/K + 647.49 J/K

                       = 93.37 J/K

Thus, we can conclude that for the given reaction \Delta H is 1243.5 kJ and \Delta S_{total} is 93.37 J/K.

6 0
2 years ago
Determinación de pH Expresa las siguientes concentraciones de [H+ ] en función del pH • [H+] = 0.001 M • [H+] = 0.002 M • [H+] =
Pavel [41]

Answer:

• pH = 3.0

• pH = 2.70

• pH = 3.61

• pH = 8.28

• pH = 1.40

Explanation:

El pH es una medida en química usada para determinar el grado de acidez o basicidad en una solución.

Se define como:

pH = -log₁₀ [H⁺]

<em>El - logaritmo de la concentración molar de H⁺</em>

<em />

Para las concentraciones de H⁺ dadas:

• [H+] = 0.001 M

pH = -log (0.001M) = 3

pH = 3.0

• [H+] = 0.002 M

pH = -log (0.002M)

pH = 2.70

• [H+] = 2.45X10-4 M

pH = -log (2.45X10-4 M )

pH = 3.61

• [H+] = 5.2X10-9 M

pH = -log (5.2X10-9 M)

pH = 8.28

• [H+] = 0.04 M

pH = -log (0.04M)

pH = 1.40

8 0
2 years ago
Given these reactions, where X represents a generic metal or metalloid 1) H2(g)+12O2(g)⟶H2O(g)ΔH1=−241.8 kJ 1) H2(g)+12O2(g)⟶H2O
Bond [772]

Answer:

ΔH = -793,6 kJ

Explanation:

It is possible to obtain ΔH of this reaction using Hess's law that says you can sum the half-reactions ΔH to obtain the ΔH of the global reaction:

If half-reactions are:

1) H₂(g) + ¹/₂O₂(g) ⟶ H₂O(g) ΔH₁ = −241.8 kJ

2) X(s) + 2Cl₂(g) ⟶ XCl₄(s) ΔH₂ = +356.9 kJ  

3) ¹/₂H₂(g) + ¹/₂Cl₂(g) ⟶ HCl(g) ΔH₃ = −92.3 kJ

4) X(s) + O₂(g) ⟶ XO₂(s) ΔH₄ = −639.1 kJ

5) H₂O(g) ⟶ H₂O(l) ΔH₅ = −44.0 kJ

The sum of (4) + 4×(3) - (2) - 2×(1) - 2×(5) is:

(4) X(s) + O₂(g) ⟶ XO₂(s) ΔH = −639.1 kJ

+4×(3) 2H₂(g) + 2Cl₂(g) ⟶ 4HCl(g) ΔH = −369,2 kJ

-(2) XCl₄(s) ⟶ X(s) + 2Cl₂(g) ΔH = -356,9 kJ

-2×(1) 2H₂O(g) ⟶ 2H₂(g) + O₂(g) ΔH = +483,6 kJ

-2×(5) 2H₂O(l) ⟶ 2H₂O(g) ΔH = +88.0 kJ

= <em>XCl₄(s) + 2H₂O(l) ⟶ XO₂(s) + 4HCl(g)</em>

Where ΔH is:

ΔH = -639,1 kJ -369,2 kJ -356,9 kJ +483,6 kJ +88,0 kJ

<em>ΔH = -793,6 kJ</em>

I hope it helps!

5 0
2 years ago
why does every human measurement have uncertainty associated with it? Why must we manage the uncertainty during calculations?
dimulka [17.4K]
Because there are many numbers of the human measurement . we must manage the uncertainly doing calculations because we can know what we are calculating.
3 0
2 years ago
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