Organic Chemistry – Some Basic Principles and Techniques Chapter-Wise Test 4

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which technique is used to purify a solid organic compound that sublimes on heating?

Sublimation is the process where a solid turns into a gas without passing through the liquid state, useful for purifying compounds like camphor or naphthalene.

Sublimation
Distillation
Crystallization
Chromatography
1

In Kjeldahl’s method, 0.5 g of an organic compound produced ammonia that neutralized 20 mL of 0.1 M \( \ce{H2SO4} \). What is the percentage of nitrogen?

Moles of \( \ce{H2SO4} \) = \( 0.02 \times 0.1 = 0.002 \). Moles of \( \ce{NH3} \) = 0.004 (2H per \( \ce{H2SO4} \)). Mass of N = \( 0.004 \times 14 = 0.056 \) g. Percentage = \( \frac{0.056}{0.5} \times 100 = 11.2\% \).

10%
11%
12%
11.2%
4

Which general formula represents alkenes?

Alkenes have one double bond and follow the formula \( \ce{C_nH_{2n}} \) (e.g., \( \ce{C2H4}, \ce{C3H6} \)).

\( \ce{C_nH_{2n+2}} \)
\( \ce{C_nH_{2n-2}} \)
\( \ce{C_nH_{n+2}} \)
\( \ce{C_nH_{2n}} \)
4

Which carbon atom in \( \ce{CH2=CH-CH2OH} \) has \( sp^2 \) hybridization?

In \( \ce{CH2=CH-CH2OH} \), the carbons in the double bond (\( \ce{CH2=CH} \)) are \( sp^2 \) hybridized; the second carbon has three sigma bonds and one pi bond.

First carbon
Third carbon
Fourth carbon
Second carbon
4

Which purification technique is most effective for separating a mixture of two liquids, one boiling at 100°C and soluble in water, the other boiling at 120°C and insoluble in water?

Differential extraction uses water to dissolve the soluble liquid (b.p. 100°C), separating it from the insoluble one (b.p. 120°C), leveraging solubility over boiling point difference.

Differential extraction
Simple distillation
Fractional distillation
Chromatography
1

A compound with \( \ce{C4H8O} \) gives a negative Lassaigne’s test for halogens and contains a carbonyl group. What functional group is present?

\( \ce{CH3CH2CH2CHO} \) (butanal, aldehyde) fits \( \ce{C4H8O} \), has a carbonyl, and no halogens, consistent with a negative Lassaigne’s test.

Ketone
Aldehyde
Ether
Alcohol
2

An organic compound with molecular formula \( \ce{C6H12} \) forms three structural isomers, one of which exhibits geometrical isomerism. What is one possible structure?

\( \ce{C6H12} \) can be hexene (e.g., \( \ce{CH3CH2CH2CH=CHCH3} \), hex-2-ene), which shows cis/trans isomerism. Hexene has three main structural isomers: hex-1-ene, hex-2-ene, hex-3-ene.

\( \ce{CH3CH2CH2CH=CHCH3} \)
\( \ce{CH3CH2CH2CH2CH3} \)
\( \ce{CH3CH2C#CCH2CH3} \)
\( \ce{CH3CH(CH3)CH2CH3} \)
1

In the Carius method, 0.22 g of a compound gave 0.431 g of \( \ce{AgCl} \). What is the percentage of chlorine?

Mass of Cl = \( \frac{35.5}{143.5} \times 0.431 = 0.1066 \) g. Percentage = \( \frac{0.1066}{0.22} \times 100 = 48.45\% \approx 48\% \).

47%
48%
49%
50%
2

Which purification method is most effective for separating a mixture of two solids with identical solubility in water but different sublimation temperatures?

Sublimation separates based on sublimation temperature differences, effective when solubility is identical but one solid sublimes and the other does not.

Crystallization
Differential extraction
Chromatography
Sublimation
4

Which compound with \( \ce{C6H12} \) has a degree of unsaturation of 1 and does not exhibit geometrical isomerism?

\( \ce{CH2=CHCH2CH2CH2CH3} \) (hex-1-ene) has one double bond (degree = 1) and no geometrical isomerism due to identical substituents (\( \ce{H} \)) on one carbon of the double bond.

\( \ce{CH3CH=CHCH2CH2CH3} \)
\( \ce{CH3CH2CH=CHCH2CH3} \)
\( \ce{CH3C(CH3)=CHCH2CH3} \)
\( \ce{CH2=CHCH2CH2CH2CH3} \)
4

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