Question

1-The lines observed in H-lamp are parts of Balmer Series. All these lines are due to a transition from various higher n value to a common n. What is this common lower n value for all these lines?

a-0

b-1

c-2

d-3

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Question 2

The bright violet line of Hg lamp has a wavelength of 435.8 nm. What is the energy of the photon associated with this emission line?

a-4.56*10^-19 J

b-4.56*10^-28 J

c-6.88*10^14 J

d-2.89*10^-31 J

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Question 3

Given: In Atomic Spectra lab, a student obtained his best-fit line equation to be y = 0.29 x + 46.8 when he plotted his Vernier reading on the y-axis and wavelength in nm on the x-axis.

Question: If the Vernier reading for a line is 229.5, what is the predicted wavelength of this line in nm? (Keep 4 sig figs with one decimal place.)

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Question 4

The only electron in a hydrogen atom moved from n=2 to n=6. What is the wavelength of photon (in nm) being associated with this transition? Use whole numbers of nm without any decimal places, such as "415", "1125".

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Question 5

Which of the following transitions of the only electron in hydrogen atom will emit longest wavelength photon?

a-n=100 to n=5

b-n=4 to n=2

c-n =2 to n=1

d-n=10 to n=20

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Question 6

A student obtained the Rydberg constant to be 2.12*10-18 J. What is the % error of the measurement? Answer as percentage and keep one decimal place.

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Question 7

Which of the following orbitals of O has the lowest energy?choose all the right answer

a-2s

b-

2p

c-3d

d-4s

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Question 8

A 100-mL sample of Pb initially has a concentration of 14.3 ppm. If this sample was diluted to 300 mL, what is the new concentration in ppm? Keep one decimal place for your answer.

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Question 9

Which of the following is directly proportional to the concentration of a solution sample?

a-intensity of light passing through

b-transmittance of light

c-	absorbance of light

d-extinct coefficient

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Question 10

When measuring the transmittance of the Fe standard solution, what is used as blank?

a-DI water

b-Tap water

c-	Fe standard solution without complexing agent

d-DI water with complexing agent

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Question 11

When intensity of light changes due to sample absorption, which of the following change accordingly?

a-wavelength

b-frenqency

c-energy of each photon

d-transmittance

Answer 1

1) 1-The lines observed in H-lamp are parts of Balmer Series. All these lines are due to a transition from various higher n value to a common n. What is this common lower n value for all these lines?

The series are

Lyman, n= 1 to n = 2,3,4....

Balmer n= 2 to n = ,3,..4., 5.

Paschen n= 3 to n = 4,5,6....

Brackett n= 4 to n = 5,6,7...

Pfund n= 5 to n = 6,7,8...

So the common lower value for balmer = 2

2) The bright violet line of Hg lamp has a wavelength of 435.8 nm. What is the energy of the photon associated with this emission line?

E = hc / lambda = hc/ wavelength

h = 6.634 X 10^-34 Js

c= 3 X 10⁸ m /s

lambda = 435.8 X 10^-10 m

Putting values

E = 6.634 X 10^-34 Js X 3 X 10⁸ m /s / 435.8 X 10^-10 m

E = 4.567 X 10^-19 Joules

3)

Given: In Atomic Spectra lab, a student obtained his best-fit line equation to be y = 0.29 x + 46.8 when he plotted his Vernier reading on the y-axis and wavelength in nm on the x-axis.

Question: If the Vernier reading for a line is 229.5, what is the predicted wavelength of this line in nm? (Keep 4 sig figs with one decimal place.)

Ans: y = 0.29 x + 46.8

y = 229.5

x = ?

229.5 = 0.29x +46.8

x = 630.0

4) Given that

n1 = 2

n2 = 6

We know

1/ = R[ (1/n1)² - (1/n2)²]

= 1.097X10⁷[1/4 - 1/36]

= 1.097X10⁷[0.25 - 0.028]

= 1.097X10⁷[0.222]

= 0.2435 X10⁷

= 1/0.244X10⁷

= 4.098X10^-7 m

= 409.8 nm

5) Which of the following transitions of the only electron in hydrogen atom will emit longest wavelength photon?

Ans: longest wavelength means lowest energy

So energy will lowest when the difference between two energy levels is lowest

n=2 to n=1

6)A student obtained the Rydberg constant to be 2.12*10-18 J. What is the % error of the measurement? Answer as percentage and keep one decimal place.

Percentage error = (Actual value - calculated value) X 100 / actual value = (2.17 - 2.12 ) X 10^-18 X 100 / 2.17 X 10-18

Percentage error = 2.3 %

7) Lowest energy " 2s

8)A 100-mL sample of Pb initially has a concentration of 14.3 ppm. If this sample was diluted to 300 mL, what is the new concentration in ppm? Keep one decimal place for your answer.

Ans:

c1 X V1 = c2 X V2

100 X 14.3 = 300 X c2

c2 = 4.77 ppm = 4.8 ppm

9) Absorbance