Questions and answers for exam Preparation

MCQs

Total Questions : 147 | Page 9 of 15 pages

Question 81. Which of the following will oscillate the fastest?

A large mass on a weak spring
A large mass on a stiff spring
A small mass on a stiff spring
A small mass on a weak spring

Discuss Question

Answer: Option C. -> A small mass on a stiff spring
Answer: (c).A small mass on a stiff spring

Question 82. Which of the following is not an IR vibrational mode?

Stretching
Scissoring
Rocking
Rolling

Discuss Question

Answer: Option D. -> Rolling
Answer: (d).Rolling

Question 83. In the equation, A = ε bc, what quantity is represented by "ε"?

Absorbtivity
Molar absorbtivity
Path length
None of these

Discuss Question

Answer: Option B. -> Molar absorbtivity
Answer: (b).Molar absorbtivity

Question 84. Why must the voltage supplied to a tungsten lamp be very stable?

Because if it wasn't, the lamp would bum out
Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage
Because the lamp will only function at a specific voltage
All of the above

Discuss Question

Answer: Option B. -> Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage
Answer: (b).Because amount of energy the lamp emits is proportional to the fourth power of the operating voltage

Question 85. For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule?

Because a change in dipole moment lowers the energy required for electronic transitions
Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment
Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching
All of the above

Discuss Question

Answer: Option B. -> Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment
Answer: (b).Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment

Question 86. Thin layer chromatography is

partition chromatography
electrical mobility of ionic species
adsorption chromatography
none of the above

Discuss Question

Answer: Option C. -> adsorption chromatography
Answer: (c).adsorption chromatography

Question 87. Internal conversion is where

the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa)
A molecule converts its excess energy to light, and emits a photon
A molecule converts excess electronic energy to vibrational energy
none of the above

Discuss Question

Answer: Option C. -> A molecule converts excess electronic energy to vibrational energy
Answer: (c).A molecule converts excess electronic energy to vibrational energy

Question 88. Why phosphorescence measurements are usually made at a low temperature?

To prevent thermal degradation of the phosphorescent species
To promote phosphorescence by slowing the rate of radiationless transfer processes
To increase the efficiency of the detector
To decease the efficiency of detector

Discuss Question

Answer: Option B. -> To promote phosphorescence by slowing the rate of radiationless transfer processes
Answer: (b).To promote phosphorescence by slowing the rate of radiationless transfer processes

Question 89. Fluorescence occurs when

a molecule returns to the electronic ground state from an excited triplet state by losing it's excess energy as a photon
a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon
a molecule lowers its vibrational energy by losing it's excess energy as a photon
none of the above

Discuss Question

Answer: Option B. -> a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon
Answer: (b).a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon

Question 90. In gas chromatography, the basis for separation of the components of the volatile material is the difference in