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WorksheetsQUIZ 2
Total questions: 11
Worksheet time: 6mins
Which process describes an electron moving from S₁ to T₁ without emitting radiation?
Fluorescence
Phosphorescence
Intersystem crossing
Vibrational relaxation
What is the typical lifetime of fluorescence emission?
Seconds to minutes
Milliseconds to seconds
Nanoseconds to microseconds
Hours
Why is phosphorescence emission longer-lived than fluorescence?
It requires less energy
Triplet → singlet transition is spin-forbidden
It occurs at shorter wavelength
It happens without any excitation
Which spectrum is usually a mirror image of the excitation spectrum?
Absorption spectrum
Fluorescence emission spectrum
Phosphorescence spectrum
UV spectrum
At high analyte concentrations, fluorescence intensity deviates from linearity because of:
Stronger fluorescence
Self-absorption and quenching
More photon emission
Longer fluorescence lifetime
Which factor usually decreases fluorescence intensity?
Cooling the sample
Increasing solvent viscosity
Raising the temperature
Adding electron-donating groups
Which substituent is most likely to quench fluorescence?
–OH
–NH₂
–OCH₃
–NO₂
Why is detection usually done at 90° to the excitation beam?
To increase excitation energy
To minimize interference from excitation light
To shorten fluorescence lifetime
To enhance quantum yield
Which instrument uses filters to select wavelengths?
Spectrophotometer
Fluorometer
Spectrofluorometer
Photomultiplier
Which inorganic ion can be detected by fluorescence spectrometry?
Na⁺
Cl⁻
Uranyl ion (UO₂²⁺)
K⁺
Second code:
I am a number.
I come after 6 but before 8.
People say I’m lucky.
What number am I?
(a)
