The quantum efficiency of a photochemical reaction is defined as _______

number of 11101ecules decomposed in a given time

ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time

number of 11101ecules decomposed in a given time

number or quanta absorbed percent time

ratio of’ molecules decomposed in a given time to the number of quanta emitted in the same time

THE_QUANTUM_EFFICIENCY_OF_A_PHOTOCHEMICAL_REACTION_IS_DEFINED_AS________?$

number of 11101ecules decomposed in a given time

ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time

number of 11101ecules decomposed in a given time

number or quanta absorbed percent time

ratio of‚Äö√Ñ√∂‚àö√ë‚àö¬• molecules decomposed in a given time to the number of quanta emitted in the same time

Which of the following will result in deviation from Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law?#

Dissociation of analyte on dilution

Change in a refractive index of medium

Dissociation of analyte on dilution

What are the appropriate reasons for the deviation from the Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law among the following?$

Very high concentration of analyte

Which regions of the light radiations of the visible ultraviolet lying between ‚Äö√Ñ√∂‚àö√ë‚àö¬® wavelength are chiefly concerned in bringing about photochemical reactions?$

19000 ‚Äö√†√∂‚àö√± and 12,000 ‚Äö√†√∂‚àö√±

1000 ‚Äö√†√∂‚àö√± and 2000 ‚Äö√†√∂‚àö√±

1500 ‚Äö√†√∂‚àö√± and 1000 ‚Äö√†√∂‚àö√±

8000 ‚Äö√†√∂‚àö√± and 2000 ‚Äö√†√∂‚àö√±

19000 ‚Äö√†√∂‚àö√± and 12,000 ‚Äö√†√∂‚àö√±

Which of the following is an incorrect statement?

When a molecule or atom in the ground state (S0) absorbs light, one electron is excited to a higher orbital level

First step in photochemistry is excited state (photoexcitation)

Photochemical reactions are caused by absorption of ultraviolet only

When a molecule or atom in the ground state (S0) absorbs light, one electron is excited to a higher orbital level

it is possible for the excited state S1 to undergo spin inversion

The fact that the fluorescence wavelength is often much longer than the irradiation wavelength (Stokes shift) is a consequence of which phenomenon?

low extinction coefficients (Lambert-Beer law)

vertical transitions (Kasha‚Äö√Ñ√∂‚àö√ë‚àö¬•s rule)

the Franck‚Äö√Ñ√∂‚àö√ë‚àö¬®Condon principle

19 + Mcqs in Photochemistry in Organic Chemistry Page 1 McqOptions

1.	A substance absorbs 2.0 x 1016 quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 1023)?
A.	50
B.	40
C.	80
D.	100
Answer» B. 40

Discussion

2.	Which of the following are the reactions in which molecules absorbing light do not themselves react but induce other molecules to react?
A.	Free radical reactions
B.	Chain reactions
C.	Reversible reactions
D.	Photosensitized reactions
Answer» E.

Discussion

3.	The quantum efficiency of a photochemical reaction is defined as _______
A.	ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time
B.	number of 11101ecules decomposed in a given time
C.	number or quanta absorbed percent time
D.	ratio of’ molecules decomposed in a given time to the number of quanta emitted in the same time
Answer» B. number of 11101ecules decomposed in a given time

Discussion

4.	Which of the following will result in deviation from Beer’s law?
A.	A, B and C
B.	B, C and D
C.	A, C and D
D.	A, B and DView Answer
Answer» B. B, C and D

Discussion

5.	A 0.1 M solution of compound A shows 50% transmittance when a cell of 1 cm width is used at λ1 nm. Another 0.1 M solution of compound B gives the optical density value of 0.1761 using 1cm cell at λ1 nm. What will be the transmittance of a solution that is simultaneously 0.1 M in A and 0.1 M in B using the same cell and at the same wave length? [log 1.301; log 1.4771; log 50 = 1.699].
A.	33.3%
B.	50%
C.	66.7%
D.	70%
Answer» B. 50%

Discussion

6.	What are the appropriate reasons for the deviation from the Beer’s law among the following?
A.	A, B and D
B.	B, C and D
C.	A, C and D
D.	A, B and CView Answer
Answer» C. A, C and D

Discussion

7.	The molar extinction coefficient of B (MW = 180) is 4 x 103 L mol-1 cm-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation?
A.	10.2
B.	13.60
C.	20.40
D.	29.12
Answer» C. 20.40

Discussion

8.	Which regions of the light radiations of the visible ultraviolet lying between – wavelength are chiefly concerned in bringing about photochemical reactions?
A.	1000 Å and 2000 Å
B.	1500 Å and 1000 Å
C.	8000 Å and 2000 Å
D.	19000 Å and 12,000 Å
Answer» D. 19000 Å and 12,000 Å

Discussion

9.	WHICH_OF_THE_FOLLOWING_ARE_THE_REACTIONS_IN_WHICH_MOLECULES_ABSORBING_LIGHT_DO_NOT_THEMSELVES_REACT_BUT_INDUCE_OTHER_MOLECULES_TO_REACT??$
A.	Free radical reactions
B.	Chain reactions
C.	Reversible reactions
D.	Photosensitized reactions
Answer» E.

Discussion

10.	THE_QUANTUM_EFFICIENCY_OF_A_PHOTOCHEMICAL_REACTION_IS_DEFINED_AS________?$
A.	ratio of molecules decomposed in a given time to the number of quanta absorbed in the same time
B.	number of 11101ecules decomposed in a given time
C.	number or quanta absorbed percent time
D.	ratio of‚Äö√Ñ√∂‚àö√ë‚àö¬• molecules decomposed in a given time to the number of quanta emitted in the same time
Answer» B. number of 11101ecules decomposed in a given time

Discussion

11.	A substance absorbs 2.0 x 10¹⁶ quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 10²³)?$
A.	50
B.	40
C.	80
D.	100
Answer» B. 40

Discussion

12.	Which of the following will result in deviation from Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law?#
A.	Change in a refractive index of medium
B.	Dissociation of analyte on dilution
C.	Polychromatic light
D.	Path length of cuvette
Answer» B. Dissociation of analyte on dilution

Discussion

13.	A 0.1 M solution of compound A shows 50% transmittance when a cell of 1 cm width is used at ‚âà√≠¬¨‚Ñ¢₁ nm. Another 0.1 M solution of compound B gives the optical density value of 0.1761 using 1cm cell at ‚âà√≠¬¨‚Ñ¢₁ nm. What will be the transmittance of a solution that is simultaneously 0.1 M in A and 0.1 M in B using the same cell and at the same wave length? [log 1.301; log 1.4771; log 50 = 1.699].$
A.	33.3%
B.	50%
C.	66.7%
D.	70%
Answer» B. 50%

Discussion

14.	What are the appropriate reasons for the deviation from the Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law among the following?$
A.	Monochromaticity of light
B.	Very high concentration of analyte
C.	Association of analyte
D.	Dissociation of analyte
Answer» C. Association of analyte

Discussion

15.	The molar extinction coefficient of B (MW = 180) is 4 x 10³ L mol^-1 cm^-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation?
A.	10.20
B.	13.60
C.	20.40
D.	29.12
Answer» C. 20.40

Discussion

16.	Which of the following instruments is used to measure the energy of the monochromatic radiation most accurately?
A.	Photoelectric cell
B.	Thermopile
C.	The potential detector
D.	The chemical actinometer
Answer» C. The potential detector

Discussion

17.	Which regions of the light radiations of the visible ultraviolet lying between ‚Äö√Ñ√∂‚àö√ë‚àö¬® wavelength are chiefly concerned in bringing about photochemical reactions?$
A.	1000 ‚Äö√†√∂‚àö√± and 2000 ‚Äö√†√∂‚àö√±
B.	1500 ‚Äö√†√∂‚àö√± and 1000 ‚Äö√†√∂‚àö√±
C.	8000 ‚Äö√†√∂‚àö√± and 2000 ‚Äö√†√∂‚àö√±
D.	19000 ‚Äö√†√∂‚àö√± and 12,000 ‚Äö√†√∂‚àö√±
Answer» D. 19000 ‚Äö√†√∂‚àö√± and 12,000 ‚Äö√†√∂‚àö√±

Discussion

18.	Which of the following is an incorrect statement?
A.	First step in photochemistry is excited state (photoexcitation)
B.	Photochemical reactions are caused by absorption of ultraviolet only
C.	When a molecule or atom in the ground state (S<sub>0</sub>) absorbs light, one electron is excited to a higher orbital level
D.	it is possible for the excited state S<sub>1</sub> to undergo spin inversion
Answer» C. When a molecule or atom in the ground state (S<sub>0</sub>) absorbs light, one electron is excited to a higher orbital level

Discussion

19.	The fact that the fluorescence wavelength is often much longer than the irradiation wavelength (Stokes shift) is a consequence of which phenomenon?
A.	low extinction coefficients (Lambert-Beer law)
B.	vertical transitions (Kasha‚Äö√Ñ√∂‚àö√ë‚àö¬•s rule)
C.	high ISC rates (El Sayed rule)
D.	the Franck‚Äö√Ñ√∂‚àö√ë‚àö¬®Condon principle
Answer» E.

Discussion

Explore topic-wise MCQs in Organic Chemistry.

A substance absorbs 2.0 x 1016 quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 1023)?

Which of the following are the reactions in which molecules absorbing light do not themselves react but induce other molecules to react?

The quantum efficiency of a photochemical reaction is defined as _______

Which of the following will result in deviation from Beer’s law?

What are the appropriate reasons for the deviation from the Beer’s law among the following?

The molar extinction coefficient of B (MW = 180) is 4 x 103 L mol-1 cm-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation?

Which regions of the light radiations of the visible ultraviolet lying between – wavelength are chiefly concerned in bringing about photochemical reactions?

WHICH_OF_THE_FOLLOWING_ARE_THE_REACTIONS_IN_WHICH_MOLECULES_ABSORBING_LIGHT_DO_NOT_THEMSELVES_REACT_BUT_INDUCE_OTHER_MOLECULES_TO_REACT??$

THE_QUANTUM_EFFICIENCY_OF_A_PHOTOCHEMICAL_REACTION_IS_DEFINED_AS________?$

A substance absorbs 2.0 x 1016 quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 1023)?$

Which of the following will result in deviation from Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law?#

What are the appropriate reasons for the deviation from the Beer‚Äö√Ñ√∂‚àö√ë‚àö¬•s law among the following?$

The molar extinction coefficient of B (MW = 180) is 4 x 103 L mol-1 cm-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation?

Which of the following instruments is used to measure the energy of the monochromatic radiation most accurately?

Which regions of the light radiations of the visible ultraviolet lying between ‚Äö√Ñ√∂‚àö√ë‚àö¬® wavelength are chiefly concerned in bringing about photochemical reactions?$

Which of the following is an incorrect statement?

The fact that the fluorescence wavelength is often much longer than the irradiation wavelength (Stokes shift) is a consequence of which phenomenon?

A substance absorbs 2.0 x 10¹⁶ quanta or radiations per second and 0.002 mole of it reacts in 1200 seconds. What is the quantum yield or the reaction (N = 6.02 x 10²³)?$

The molar extinction coefficient of B (MW = 180) is 4 x 10³ L mol^-1 cm^-1. One-liter solution of C which contains 0.1358 g pharmaceutical preparation of B, shows an absorbance of 0.411 in a 1 cm quartz cell. What is the percentage (w/w) of B in the pharmaceutical preparation?