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3 years ago

Which atom in the ground state has a partially filled second electron shell?

Chemistry

2 answers:

adell [148]3 years ago

7 0

The answer is lithium.

This is because it has an electron configuration of 1s2, 2s1 (also written as [He]2s1)

serious [3.7K]3 years ago

4 0

Atoms have electrons filled in energy shells.
1. H - hydrogen atom has one electron in the First energy shell. Therefore hydrogen has a partially filled first energy shell

2.Li - Li electron configuration is 2,1
The outermost energy shell is the second energy shell in which there is only one electron
Therefore the second energy shell is partially filled. This is the correct answer

3. K - electron configuration is 2,8,8,1
The outermost energy shell is the fourth energy shell which is partially filled. The second energy shell is completely filled

4.Na - electron configuration is 2,8,1
The outermost energy shell is the third energy shell which is partially filled
Second energy shell is completely filled

From the given options Li is the only element with a partially filled second energy shell
Answer is Li

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This protein takes oxygen from hemoglobin in order to

never [62]

Answer:

i'm pretty sure it's 'transport oxygen from the lungs to tissues around the body'

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3 years ago

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Which statement describes what it means for a planet’s orbit to be elliptical?(1 point)

sesenic [268]

Using the concepts of ellipse and the universal law of gravitation it can be found that the correct answer is:

a) The planet’s path around the sun is not a perfect circle and is shaped like an oval.

The universal gravitational law establishes that the force between two bodies is proportional to their mass and inversely proportional to the square of their distance, when one of the bodies has much greater mass than the other, the body with greater mass experiences less rotational acceleration.

In the case of the sun and the planet, the sun is many orders of magnitude more massive than the planets, therefore, it is almost fixed in the center and the lighter planets rotate around it, where the sun is in the focus of the ellipse orbit.

In the special case that the two foci coincide, there is a circular movement, but the most general is that there is some separation between the foci, so the movement is elliptical with the sun located in one of the foci.

Let's analyze the claims of this exercise

a) True. When the orbit is not a perfect circle, you have an elliptical orbit, this is the most common case.

b) False. The axis of the planet has no effect on the orbit, it affects the intensity of the radiation that reaches the planets

c) False. Circular motion is a special case of elliptical motion when the two foci coincide

d) False. The axis of the planet influences the intensity of radiation reaching the surface, but not the shape of the orbit of the plant.

Using the concepts of ellipse it can be found that the correct answer is:

a) The planet’s path around the sun is not a perfect circle and is shaped like an oval.

learn more about planetary motion here:

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3 years ago

Complete and balance the following acid-base equations:

Alchen [17]

Answer:

a) $HClO_4 (aq) + LiOH \rightarrow LiClO_4 + H_2O$

b) $H_2SO_4(aq) + 2NaOH(aq) \rightarrow Na_2SO_4 (aq) + 2H_2O (l)$

c) $Ba(OH)2 + 2HF\rightarrow BaF_2 + 2H_2O$

Explanation:

when $HClO_4$ is added to LiOH, lithium chlorate and water is formed.

$HClO_4 (aq) + LiOH \rightarrow LiClO_4 + H_2O$

Balancing of above reaction,

It can be seen that all the atoms in both the sides are balanced. so it is a balanced reaction.

(b) When aqueous $H_2SO_4$ is added to NaOH, $Na_2SO_4$ and $H_2O$ is formed. It is a neutrilization reaction.

$H_2SO_4(aq) + NaOH(aq) \rightarrow Na_2SO_4 (aq) + H_2O (l)$

Balancing of above reaction,

First balance all the atoms except O and H

S atom is already balanced in either side

No. of Na atom in left hand side = 1

No. of Na atom in right hand side = 2

So multiply NaOH by 2, now the reaction becomes:

$H_2SO_4(aq) + 2NaOH(aq) \rightarrow Na_2SO_4 (aq) + H_2O (l)$

No. of O atoms in left hand side = 6

No. of O atoms in right hand side = 5

So multiply H2O by 2, now the reaction becomes:

$H_2SO_4(aq) + 2NaOH(aq) \rightarrow Na_2SO_4 (aq) + 2H_2O (l)$

Now, it can been seen that all the atoms are balanced.

c) When $Ba(OH)2$ reacts with HF, baroum fluoride and water is formed.

$Ba(OH)2 + HF\rightarrow BaF_2 + H_2O$

Balancing of above reaction,

Barium atoms are already balanced on either side.

No. of F atoms on left hand side = 1

No. of F atoms on right hand side = 2

So, multiply HF by 2, now reaction becomes

$Ba(OH)2 + 2HF\rightarrow BaF_2 + H_2O$

In order to balance H and O on either side, multiply H2O by 2.

$Ba(OH)2 + 2HF\rightarrow BaF_2 + 2H_2O$

7 0

3 years ago

Which of these does not describe a significant ethical dilemma in the drug industry?

nikitadnepr [17]

D as it only has a negative effect when being used and it is small at that anyway.

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3 years ago

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What is the freezing point of a solution of 498mL of water (solute) dissolved in 2.50 L of ethanol (solvent), C2H5OH? The densit

jok3333 [9.3K]

Answer:

Freezing T° of solution is -142.4°C

Explanation:

This excersise is about colligative properties, in this case freezing point depression,

ΔT = Kf . m . i

Where ΔT = Freezing T° of solvent - Freezing T° of solution

Kf = Cryoscopic constant

m = mol/kg (molality)

i = Number of ions dissolved.

Water is not ionic, so i = 1

Let's find out m.

We determine mass of water, by density

498ml . 1 g/mL = 498 g

We convert the mass of water to moles → 498 g . 1mol/18g = 27.6 moles

We determine mass of solvent by density

2500 mL . 0.789 g/mL = 1972.5 g

Notice, we had to convert L to mL to cancel units.

1 cm³ = 1 mL

We convert the mass from g to kg → 1972.5 g . 1kg /1000g = 1.97kg

We determine m = mol/kg → 27.6mol / 1.97kg = 13.9 m

Kf for ethanol is: 1.99 °C/m

Freezing T° for ethanol is: -114.6°C

We replace at formula: - 114.6°C - Freezing T° solution = 1.99 °C/m . 13.9 m . 1

- 114.6°C - Freezing T° solution = 27.8 °C

- Freezing T° solution = 27.8°C + 114.6°C

Freezing T° Solution = - 142.4 °C

7 0

3 years ago