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MCQ on UV-Visible spectroscopy: Page-11

1. Collimator is a device used in monochromators to

Focus the required range of wavelength of radiation

(B)Eliminate interferences from other amines

(C) Eliminate reflection and scattering

(D) Focus the incident radiation parallel on to the dispersing device

2. The lmax for the following compound is
2-Amino-4-hydroxybenzaldehyde

(A) 255

(B) 275

(C) 249

(D) 288

Base value of benzaldehyde is 250 nm. Hydroxyl group at para position has increment of 25 nm while amino group at ortho position has 13 nm as increment. Therefore the final calculated value will be 250 + 25 + 13=288 nm.

3. Which of the following leads to chemical deviation from Beer’s law

(A) Change in refractive index

(B) Change in pH of the solution

(C) Polychromatic radiation

(D) Both a and b

4. All of the following expressions are correct, except

(A) T=I t/I 0

(B) A=-logT

(C) A=2 - log%T

(D) A=-log(I0 /It)

5. Solvatochromism is the ability of a substance to change colour due to

(A) A change in wavelength of the incident radiation

(B) A change in the solvent viscosity

(C) A change in molecular weight of the substance

(D) A change in the solvent polarity