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2 years ago

Which electron configuration represents a selenium atom in an excited state?(1) 2-7-18-6(2) 2-7-18-7(3) 2-8-18-6(4) 2-8-18-7

1 answer:

5 0

(2) 2 - 7 - 18 - 7 does, because the electron from the L shell jumped to the N shell, which requires energy.

The rest of them are either different types of atoms (different elements) or are not the excited state (ground state)

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Enter your answer in the provided box. an aqueous solution containing 10 g of an optically pure substance was diluted to 500 ml

sladkih [1.3K]

Answer:

[α] = -77.5° / $\frac{\textup{dm-g}}{\textup{mL}}$

Explanation:

Given;

Mass of optically pure substance in the solution = 10 g

Volume of water = 500 mL

Length of the polarimeter, l = 20 cm = 20 × 0.1 dm = 2 dm

measured rotation = - 3.10°

Now,

The specific rotation ( [α] ) is given as:

[α] = $\frac{\alpha}{c\times l}$

here,

α is the measured rotation = -3.10°

c is the concentration

c = $\frac{\textup{Mass of optically pure substance in the solution}}{\textup{Volume of water}}$

c = $\frac{10}{500}$

c = 0.02 g/mL

on substituting the values, we get

[α] = $\frac{-3.10^o}{0.02\times2}$

[α] = -77.5° / $\frac{\textup{dm-g}}{\textup{mL}}$

7 0

3 years ago

The solubility of CO2 in water is 0.161 g/100 mL at 20oC and a partial pressure of CO2 of 760 mmHg. What partial pressure of CO2

Schach [20]

Answer: The partial pressure of carbon dioxide having solubility 0.886g/100mL is 4182.4 mmHg

Explanation:

Henry's law states that the amount of gas dissolved or molar solubility of gas is directly proportional to the partial pressure of the liquid.

The equation given by Henry's law is:

$C_{CO_2}=K_H\times p_{CO_2}$ ......(1)

where,

$C_{CO_2$ = solubility of carbon dioxide in water = 0.161 g/100 mL

$K_H$ = Henry's constant = ?

$p_{CO_2}$ = partial pressure of carbon dioxide = 760 mmHg

Putting values in equation 1, we get:

$760mmHg=K_H\times 0.161g/100mL\\\\K_H=\frac{760mmHg}{0.161g/100mL}=4720.5g.mmHg/100mL$

Now, calculating the pressure of carbon dioxide using equation 1, we get:

$C_{CO_2$ = solubility of carbon dioxide in water = 0.886 g/100 mL

$K_H$ = Henry's constant = 4720.5 g.mmHg/100 mL

$p_{CO_2}$ = partial pressure of carbon dioxide = ?

Putting values in equation 1, we get:

$p_{CO_2}=4720.5g.mmHg/100mL\times 0.886g/100mL=4182.4mmHg$

Hence, the partial pressure of carbon dioxide having solubility 0.886g/100mL is 4182.4 mmHg

4 0

3 years ago

What is advantage of using single fixed pulley although it doesnot multiply force?

luda_lava [24]

A single fixed pulley is used to lift load by changing the direction of the lifting force. Even though a single fixed pulley has no mechanical gain in that, the effort applied is greater than the load, it is preferred in use since you do not have to pull or push the pulley up and down.

4 0

2 years ago

Read 2 more answers

Describe the difference between a ball-and-stick model and a space-filling model of a compound.

Lisa [10]

A space-filling model shows the relative amount of space each atom takes up. In other words, a space-filling model can show relative sizes of atoms. However, unlike ball-and-stick or structural models, space-filling models do not show bond lengths clearly. Bonds are not really like sticks in a ball-and-stick model.

4 0

3 years ago

Which of the following is an anion? A. O^2- C. Al^3+ D. H

kifflom [539]

The correct answer is A. O^2-

6 0

2 years ago