Organic Chemistry Practice Test 3

1. The ultraviolet spectrum of benzonitrile shows a secondary absorption band at 271 nm. If a solution of benzonitrile in water, with a concentration of 1x10^-4 molar solution is examined at 271 nm, what will be the absorbance reading (ℇ = 1000) and what will be the intensity ratio, I_O/I, respectively?

0.2, 2.26

0.4, 4.26

0.3, 3.26

0.1, 1.26

2. Which of the following statements is correct for alkyl halide?

In most unimolecular reactions of alkyl halide E1 reaction is favoured over SN1 reaction

Alkyl halide will always show S_N1 mechanism

In unimolecular reaction, increasing the temperature donot favours E1 mechanism

As branching at carbon increases, E1 mechanism is favoured as compared to S_N1 mechanism

3. What is the oxidation state of molybdenum in [η⁷-tropylium) Mo(CO)₃]⁺?

-1

4. What are the main criteria on which mass spectrometer used for?

Properties of sample

Concentration of elements in the sample

Composition in sample

Relative mass of atoms

5. In which state of matter mass spectroscopy is being performed?

plasma

solid

liquid

gaseous

6. Which incorrect about alkyl bromide having molecular formula C₅H₁₁Br?

Only one is incapable of reacting by the E2 mechanism

One isomeric alkyl bromide undergoes E1 elimination at the fastest rate

Only one isomer gives a single alkene on E2 elimination

2-Bromopentane gives the most complex mixture of alkenes on E2 elimination

7. What is the correct order of λmax for n --> σ* transition?

R-OH > R-SH > R-NH₂

R-OH < R-NH₂ < R-SH

R-OH < R-SH < R-NH₂

R-OH > R-NH₂ > R-SH

8. How many peaks are expected in low-resolution NMR spectrum of vinyl chloride and ethyl cyclopropane?

5,3

3,6

6,3

3,5

9. The 1_H NMR spectrum of CH₃OCHCICH₂Cl will exhibit ________

A three proton triplet. One proton triplet and a two proton triplet

A three proton singlet. One proton triplet and a two proton doublet

A three proton singlet. One proton singlet and a two proton doublet

A three proton doublet. One proton singlet and a two proton doublet

10. Which of the following will result in deviation from Beer's law?

(A) Change in a refractive index of medium 
(B) Dissociation of analyte on dilution
(C) Polychromatic light                                  
(D) Path length of cuvette

A, C and D

B, C and D

A, B and D

A, B and C