Organic Chemistry – Some Basic Principles and Techniques Chapter-Wise Test 9

Correct answer Carries: 4.

Wrong Answer Carries: -1.

In the Carius method, 0.3 g of a compound gave 0.574 g of \( \ce{AgBr} \). What is the percentage of bromine?

Molar mass of \( \ce{AgBr} = 188 \) g/mol, Br = 80 g/mol. Mass of Br = \( \frac{80}{188} \times 0.574 = 0.244 \) g. Percentage = \( \frac{0.244}{0.3} \times 100 = 81.33\% \).

78%
80%
82%
81%
4

What is the hybridization of the carbon atom in \( \ce{CH3COOH} \) that is double-bonded to oxygen?

In \( \ce{CH3COOH} \) (acetic acid), the carbonyl carbon (\( \ce{C=O} \)) has three sigma bonds (to O, OH, and CH3) and one pi bond, indicating \( sp^2 \) hybridization.

\( sp^2 \)
\( sp^3 \)
\( sp \)
\( sp^3d \)
1

How many \( \pi \) bonds are present in \( \ce{CH3CH=CHCH=CH2} \)?

In \( \ce{CH3CH=CHCH=CH2} \) (penta-1,3-diene), each of the two double bonds has 1 \( \pi \) bond, totaling 2 \( \pi \) bonds.

1
2
3
4
2

In Kjeldahl’s method, 0.36 g of a compound produced ammonia that neutralized 25 mL of 0.1 M \( \ce{H2SO4} \). What is the percentage of nitrogen?

Moles of \( \ce{H2SO4} \) = \( 0.025 \times 0.1 = 0.0025 \). Moles of \( \ce{NH3} \) = 0.005 (2H per \( \ce{H2SO4} \)). Mass of N = \( 0.005 \times 14 = 0.07 \) g. Percentage = \( \frac{0.07}{0.36} \times 100 \approx 19.44\% \), which rounds to 19%.

18%
20%
21%
19%
4

Which technique separates components based on their adsorption on a solid surface?

Adsorption chromatography separates compounds based on their differential adsorption on a stationary phase like silica gel.

Partition chromatography
Distillation
Sublimation
Adsorption chromatography
4

Which carbon in \( \ce{CH3CH2CH=CH2} \) has \( sp^2 \) hybridization?

In \( \ce{CH3CH2CH=CH2} \), the third carbon (\( \ce{CH=} \)) is part of the double bond, with three sigma bonds and one pi bond, indicating \( sp^2 \) hybridization.

First carbon
Second carbon
Fourth carbon
Third carbon
4

Which of the following has the highest number of \( \pi \) bonds?

\( \ce{CH2=CH-C#CH} \) has 3 \( \pi \) bonds: 1 from \( \ce{CH2=CH} \), 2 from \( \ce{C#CH} \), more than the others.

\( \ce{CH2=CH2} \)
\( \ce{CH3CH=CH2} \)
\( \ce{CH3C#CH} \)
\( \ce{CH2=CH-C#CH} \)
4

A compound with molecular formula \( \ce{C4H8O2} \) is a functional isomer of \( \ce{CH3CH2COOH} \) and contains an ester group. What is its IUPAC name?

\( \ce{CH3CH2COOH} \) (propanoic acid) has \( \ce{C3H6O2} \), corrected to \( \ce{C4H8O2} \) as \( \ce{CH3CH2CH2COOH} \) (butanoic acid). Its ester isomer is \( \ce{CH3COOCH2CH3} \) (ethyl ethanoate).

Ethyl ethanoate
Methyl propanoate
Ethyl methanoate
Propyl methanoate
1

In the Dumas method, nitrogen is estimated by measuring the volume of which gas at STP?

The Dumas method involves heating the compound to release nitrogen gas (\( \ce{N2} \)), which is collected and measured at STP.

\( \ce{CO2} \)
\( \ce{N2} \)
\( \ce{NH3} \)
\( \ce{O2} \)
2

In the Carius method, 0.15 g of a compound gave 0.287 g of \( \ce{AgCl} \). If the same sample in Kjeldahl’s method neutralized 10 mL of 0.1 M \( \ce{H2SO4} \), what is the percentage of chlorine?

Mass of Cl = \( \frac{35.5}{143.5} \times 0.287 = 0.071 \) g. Percentage = \( \frac{0.071}{0.15} \times 100 = 47.33\% \approx 47\% \). Kjeldahl’s data is for nitrogen, irrelevant here.

46%
47%
48%
49%
2

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