Grade 10 : Science - 4. Carbon Compounds (Set 2) | Concept of Maths

Question 1

1. Q1. An industrial laundry quality tester evaluates two cleaning agents, $A$ and $B$, in a water sample containing $200\text{ ppm}$ of $Ca^{2+}$ and $Mg^{2+}$ ions (hard water). Agent $A$ forms a sticky, insoluble precipitate (scum) and fails to produce lather, while Agent $B$ lathers effortlessly without forming any precipitate. What are the chemical identities of the hydrophilic heads of Agent $A$ and Agent $B$ respectively?

A) A $-COO^-Na^+$ and $-SO_4^-Na^+$ (or $-SO_3^-Na^+$)

B) B $-SO_3^-Na^+$ and $-COO^-Na^+$

C) C $-NH_4^+$ and $-COO^-Na^+$

D) D $-SO_4^-Na^+$ and $-NH_4^+$

Answer

Correct Answer: A

Question 2

2. Q2. An organic chemist is synthesizing a sweet-smelling, pear-flavored ester known as pentyl ethanoate ($C_7H_{14}O_2$) by reacting an alcohol $X$ and a carboxylic acid $Y$ in the presence of concentrated sulfuric acid. If the molecular mass of alcohol $X$ is $88\text{ g/mol}$ and that of carboxylic acid $Y$ is $60\text{ g/mol}$, identify the IUPAC names of $X$ and $Y$.

A) A X: Butan-1-ol, Y: Propanoic acid

B) B X: Pentan-1-ol, Y: Ethanoic acid

C) C X: Propan-1-ol, Y: Butanoic acid

D) D X: Hexan-1-ol, Y: Methanoic acid

Answer

Correct Answer: B

Question 3

3. Q3. In a municipal waste treatment plant, anaerobic digestion of organic matter produces biogas, which primarily consists of methane ($CH_4$). If $160\text{ kg}$ of pure methane undergoes complete combustion in the presence of excess oxygen, calculate the mass of water vapor produced and identify the thermodynamic nature of this reaction.

Question 4

4. Q4. A food safety inspector titrates a $10\text{ mL}$ sample of commercial vinegar (aqueous solution of ethanoic acid) to determine its purity. The sample requires exactly $12\text{ mL}$ of a $1\text{ M } NaOH$ solution for complete neutralization. What is the concentration (w/v %) of ethanoic acid in this vinegar, and does it fall within the standard commercial vinegar range of $5\% - 8\%$? (Molar mass of ethanoic acid = $60\text{ g/mol}$)

A) A $4.5\%$, No (Below standard)

B) B $7.2\%$, Yes (Within standard)

C) C $9.6\%$, No (Above standard)

D) D $6.0\%$, Yes (Within standard)

Answer

Correct Answer: B

Question 5

5. Q5. A polymer engineer is synthesizing a novel green plastic. She starts with monomer $A$, which is a gaseous unsaturated hydrocarbon with a carbon-to-hydrogen ratio of $1:2$ and a molecular mass of $42\text{ g/mol}$. She subjects $A$ to catalytic hydrogenation in the presence of nickel to yield compound $B$. Identify the structural formulas of $A$ and $B$.

A) A $A: CH_3-CH=CH_2$, $B: CH_3-CH_2-CH_3$

B) B $A: CH_2=CH_2$, $B: CH_3-CH_3$

C) C $A: CH \equiv CH$, $B: CH_2=CH_2$

D) D $A: CH_3-CH_2-CH=CH_2$, $B: CH_3-CH_2-CH_2-CH_3$

Answer

Correct Answer: A

Question 6

6. Q6. To prevent the industrial misuse of pure ethanol, authorities "denature" it by blending it with highly toxic substances. A forensic laboratory analyzes a seized batch of denatured spirit and confirms the presence of a poisonous homologue of ethanol containing only 1 carbon atom, alongside a blue dye. Identify this poisonous homologue and describe its lethal biochemical pathway in the human body.

A) A Methanoic acid; it severely acidifies the bloodstream leading to systemic shock.

B) B Methanol; it is oxidized to methanal in the liver, which coagulates cellular protoplasm and damages the optic nerve.

C) C Propan-2-ol; it induces sudden dehydration of cells within the digestive tract.

D) D Acetone; it directly targets and dissolves cell membranes in the renal tubules.

Answer

Correct Answer: B

Question 7

7. Q7. A mechanic tests the tailpipe emissions of an older vehicle with a malfunctioning catalytic converter. He detects a significant concentration of an unsaturated hydrocarbon gas $X$ (molecular formula $C_2H_4$) that decolorizes red-brown bromine water instantly. What is the nature of the covalent bonding in $X$, and what is the IUPAC name of the product formed upon its reaction with bromine water?

A) A Triple bond; 1,1,2,2-tetrabromoethane

B) B Double bond; 1,2-dibromoethane

C) C Single bond; bromoethane

D) D Double bond; bromomethane and methanol

Answer

Correct Answer: B

Question 8

8. Q8. In a practical chemistry workshop, students heat $10\text{ g}$ of a glyceryl ester of stearic acid (tristearin, $(C_{17}H_{35}COO)_3C_3H_5$) with an excess of aqueous sodium hydroxide ($NaOH$). They obtain sodium stearate (soap) and a highly viscous, sweet-tasting organic byproduct $Y$. What is the IUPAC name of byproduct $Y$, and how is the soap separated from it?

A) A Propane-1,2,3-triol; separated by adding Sodium Chloride ($NaCl$) to precipitate the soap.

B) B Ethanol; separated by simple fractional distillation.

C) C Propan-2-ol; separated by adding Calcium Chloride ($CaCl_2$).

D) D Ethane-1,2-diol; separated by simple filtration directly.

Answer

Correct Answer: A

Question 9

9. Q9. During fractional distillation of crude oil, a refinery isolates a pure gaseous alkane fraction. A laboratory technician measures its vapor density to be $29$. Determine the molecular formula of this alkane and calculate the number of structural isomers it can exhibit. (Hint: $\text{Molecular Mass} = 2 \times \text{Vapor Density}$ )

A) A $C_3H_8$, 1 isomer

B) B $C_4H_{10}$, 2 isomers

C) C $C_5H_{12}$, 3 isomers

D) D $C_4H_8$, 4 isomers

Answer

Correct Answer: B

Question 10

10. Q10. During a school laboratory practical, a student accidentally spills a sweet-smelling liquid organic compound $Z$ onto a small piece of active sodium metal. No reaction or effervescence is observed. However, another student spills a sour-smelling organic compound $W$ onto the sodium metal, producing rapid effervescence of a gas that burns with a characteristic "pop" sound. Identify compounds $Z$ and $W$.

A) A Z: Ethanoic acid, W: Ethanol

B) B Z: Ethyl ethanoate, W: Ethanoic acid

C) C Z: Ethanol, W: Ethyl ethanoate

D) D Z: Propanone, W: Methanol

Answer

Correct Answer: B

Accepted Answer

Correct Answer: B

Grade 10 : Science - 4. Carbon Compounds (Set 2) | Concept of Maths