Question 1

1. An industrial laundry quality tester evaluates two cleaning agents, A and B, in a water sample containing 200 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: Option A

Question 2

2. 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 g/mol and that of carboxylic acid Y is 60 g/mol, identify the IUPAC names of X and Y.

Question 3

3. In a municipal waste treatment plant, anaerobic digestion of organic matter produces biogas, which primarily consists of methane ($CH_4$). If 160 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.

A) A 180 kg, Endothermic substitutionB) B 360 kg, Exothermic combustionC) C 320 kg, Endothermic additionD) D 720 kg, Exothermic substitution

Answer

✓ Correct Answer: Option B

Question 4

4. A food safety inspector titrates a 10 mL sample of commercial vinegar (aqueous solution of ethanoic acid) to determine its purity. The sample requires exactly 12 mL of a 1m 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 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: Option B

Question 5

5. 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 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: Option A

Question 6

6. 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: Option B

Question 7

7. 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-tetrabromoethaneB) B Double bond; 1,2-dibromoethaneC) C Single bond; bromoethaneD) D Double bond; bromomethane and methanol

Answer

✓ Correct Answer: Option B

Question 8

8. In a practical chemistry workshop, students heat 10 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: Option A

Question 9

9. 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: $Molecular Mass = 2 \times Vapor Density$ )

A) A $C_3H_8$, 1 isomerB) B $C_4H_{10}$, 2 isomersC) C $C_5H_{12}$, 3 isomersD) D $C_4H_8$, 4 isomers

Answer

✓ Correct Answer: Option B

Question 10

10. 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: EthanolB) B Z: Ethyl ethanoate, W: Ethanoic acidC) C Z: Ethanol, W: Ethyl ethanoateD) D Z: Propanone, W: Methanol

Answer

✓ Correct Answer: Option B

Accepted Answer

✓ Correct Answer: Option B

Grade 10 : Science - 4. Carbon Compounds (Set 2)