PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions for Chemistry

Why do we require artificial sweetening agents?

What are food preservatives?

Why is use of aspartame limited to cold foods and drinks?

What are artificial sweetening agents? Give two examples.

Name a sweetening agent used in the preparation of sweets for a diabetic patient.

What problem arises in using alitame as artificial sweetener?

Complete the following reaction:

\[\ce{C6H5NH2 + CHCl3 + alc. KOH ->}\]

What is meant by the following term? Give an example of the reaction in the following case.

Aldol

Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.

1. Methanal
2. 2-Methylpentanal
3. Benzaldehyde
4. Benzophenone
5. Cyclohexanone
6. 1-Phenylpropanone
7. Phenylacetaldehyde
8. Butan-1-ol
9. 2, 2-Dimethylbutanal

How will you convert ethanal into the following compound?

Butane-1, 3-diol

How will you convert ethanal into the following compound?

But-2-enal

Write structural formulas and names of four possible aldol condensation products from propanal and butanal. In each case, indicate which aldehyde acts as nucleophile and which as electrophile.

How will you bring about the following conversion in not more than two steps?

Ethanol to 3-Hydroxybutanal

How will you bring about the following conversion in not more than two steps?

Benzaldehyde to 3-Phenylpropan-1-ol

Describe the following:

Cross aldol condensation

Complete the synthesis by giving missing starting material, reagent or product.

\[\begin{array}{cc}
\ce{C6H5CHO}\phantom{............}\\
\phantom{........}\ce{+\phantom{......}\ce{->[dil.NaOH][\Delta]}}\phantom{...}\\
\ce{CH3CH2CHO}\phantom{............}
\end{array}\]

Give the structure of the product you would expect when the following alcohol reacts with HCl–ZnCl₂.

Butan-1-ol

Give two reactions that show the acidic nature of phenol.

Explain how does the −OH group attached to a carbon of benzene ring activate it towards electrophilic substitution?

Predict all the alkenes that would be formed by dehydrohalogenation of the following halide with sodium ethoxide in ethanol and identify the major alkene:

1-Bromo-1-methylcyclohexane