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Chemistry (Secondary & College Level) (Chemistry) Solved Questions & Notes (2026) - Apex Rankers

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280 Total Solved Questions
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Chemistry (Secondary & College Level)

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Q. 1 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What catalyst is industrially used in the Contact Process for manufacturing Sulfuric Acid (H2SO4)?
A
Vanadium(V) oxide (V2O5)
✓ Correct
B
Finely divided Iron (Fe)
C
Nickel (Ni)
D
Platinum gauze
💡 Step-by-Step Explanation & Concept Rationale
V2O5 catalyzes the oxidation of SO2 to SO3 at 450 °C in the Contact Process.
Q. 2 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What catalyst is employed in the catalytic hydrogenation of vegetable oil to make margarine / vegetable ghee?
A
Finely divided Nickel (Ni) at 150–200 °C
✓ Correct
B
Copper (Cu)
C
Iron oxide
D
Zinc dust
💡 Step-by-Step Explanation & Concept Rationale
Nickel catalyst facilitates addition of H2 across alkene double bonds in fatty acids.
Q. 3 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
Which gas is commonly known as 'Laughing Gas' in clinical anesthesia and propellant applications?
A
Dinitrogen Monoxide (Nitrous Oxide - N2O)
✓ Correct
B
Nitrogen Dioxide (NO2)
C
Nitric Oxide (NO)
D
Ammonia (NH3)
💡 Step-by-Step Explanation & Concept Rationale
N2O is an anesthetic and analgesic inhalation gas widely termed laughing gas.
Q. 4 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What is the primary chemical component of Plaster of Paris?
A
Calcium Sulfate Hemihydrate (CaSO4 . 1/2 H2O)
✓ Correct
B
Calcium Carbonate (CaCO3)
C
Calcium Hydroxide (Ca(OH)2)
D
Calcium Oxide (CaO)
💡 Step-by-Step Explanation & Concept Rationale
Plaster of Paris is produced by heating gypsum (CaSO4 . 2H2O) to form calcium sulfate hemihydrate.
Q. 5 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What functional group is characteristic of Carboxylic Acids, Esters, and Ketones respectively?
A
-COOH, -COOR, and -C(=O)-
✓ Correct
B
-CHO, -OH, and -NH2
C
-CONH2, -CN, and -SH
D
-O-, -X, and -NO2
💡 Step-by-Step Explanation & Concept Rationale
Carboxylic acids contain carboxyl (-COOH), esters contain alkoxycarbonyl (-COOR), and ketones contain carbonyl between carbons (-C(=O)-).
Q. 6 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What reagent is used to distinguish Aldehydes from Ketones via formation of a shiny silver mirror?
A
Tollens' Reagent (Ammoniacal Silver Nitrate)
✓ Correct
B
Benedict's Solution
C
Lucas Reagent
D
Fehling's Solution B
💡 Step-by-Step Explanation & Concept Rationale
Aldehydes reduce Tollens' reagent [Ag(NH3)2]+ to metallic silver (silver mirror), while ketones do not oxidize easily.
Q. 7 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What test distinguishes primary, secondary, and tertiary alcohols based on the appearance of cloudiness with ZnCl2/HCl?
A
Lucas Test
✓ Correct
B
Biuret Test
C
Molisch Test
D
Iodoform Test
💡 Step-by-Step Explanation & Concept Rationale
Lucas reagent (anhydrous ZnCl2 in concentrated HCl) forms insoluble alkyl chloride immediately for tertiary alcohols, in 5 mins for secondary, and not at room temp for primary.
Q. 8 Chemistry (Secondary & College Level)
Difficulty: HARD (1 Mark)
What is the major organic product formed when Ethanol is dehydrated with concentrated H2SO4 at 170 °C?
A
Ethene (Ethylene - CH2=CH2)
✓ Correct
B
Diethyl ether (C2H5-O-C2H5)
C
Ethanoic acid
D
Ethyl hydrogen sulfate
💡 Step-by-Step Explanation & Concept Rationale
At 170 °C, concentrated sulfuric acid undergoes intramolecular elimination to form ethene. (At 140 °C, intermolecular dehydration yields diethyl ether).
Q. 9 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
Which law of chemical combination states that when elements combine, they do so in simple whole-number mass ratios?
A
Law of Definite Proportions (Proust's Law)
✓ Correct
B
Law of Conservation of Mass
C
Dalton's Law of Partial Pressures
D
Henry's Law
💡 Step-by-Step Explanation & Concept Rationale
Proust's law states that a chemical compound always contains exactly the same proportion of elements by mass.
Q. 10 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What is the oxidation state of Chromium in Potassium Dichromate (K2Cr2O7)?
A
+6
✓ Correct
B
+3
C
+7
D
+4
💡 Step-by-Step Explanation & Concept Rationale
In K2Cr2O7: 2(+1) + 2(Cr) + 7(-2) = 0 => 2Cr - 12 = 0 => Cr = +6.
Q. 11 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What is the oxidation state of Manganese in Potassium Permanganate (KMnO4)?
A
+7
✓ Correct
B
+2
C
+4
D
+6
💡 Step-by-Step Explanation & Concept Rationale
In KMnO4: (+1) + (Mn) + 4(-2) = 0 => Mn - 7 = 0 => Mn = +7.
Q. 12 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What is the conjugate base of the Bicarbonate ion (HCO3-)?
A
Carbonate ion (CO3^2-)
✓ Correct
B
Carbonic acid (H2CO3)
C
Hydroxide (OH-)
D
Carbon dioxide (CO2)
💡 Step-by-Step Explanation & Concept Rationale
Removing a proton H+ from HCO3- leaves its conjugate base CO3^2-.
Q. 13 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What type of bond exists between nitrogen atoms in a Diatomic Nitrogen molecule (N2)?
A
One sigma bond and two pi bonds (Triple Covalent Bond)
✓ Correct
B
Three sigma bonds
C
Two ionic bonds
D
One single covalent bond
💡 Step-by-Step Explanation & Concept Rationale
:N≡N: features a strong triple bond (one sigma, two pi) with high bond dissociation energy (945 kJ/mol).
Q. 14 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What is the term for compounds having identical molecular formulas but different spatial three-dimensional arrangements?
A
Stereoisomers (Enantiomers & Diastereomers)
✓ Correct
B
Structural isomers
C
Homologs
D
Allotropes
💡 Step-by-Step Explanation & Concept Rationale
Stereoisomers share identical connectivity but differ in spatial orientation.
Q. 15 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
Which noble gas is the most abundant in Earth's atmosphere (~0.93% by volume)?
A
Argon (Ar)
✓ Correct
B
Helium (He)
C
Neon (Ne)
D
Krypton (Kr)
💡 Step-by-Step Explanation & Concept Rationale
Argon accounts for ~0.93% of dry atmospheric air, making it the third most abundant atmospheric gas after N2 and O2.
Q. 16 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What catalyst is industrially used in the Contact Process for manufacturing Sulfuric Acid (H2SO4)?
A
Vanadium(V) oxide (V2O5)
✓ Correct
B
Finely divided Iron (Fe)
C
Nickel (Ni)
D
Platinum gauze
💡 Step-by-Step Explanation & Concept Rationale
V2O5 catalyzes the oxidation of SO2 to SO3 at 450 °C in the Contact Process.
Q. 17 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What catalyst is employed in the catalytic hydrogenation of vegetable oil to make margarine / vegetable ghee?
A
Finely divided Nickel (Ni) at 150–200 °C
✓ Correct
B
Copper (Cu)
C
Iron oxide
D
Zinc dust
💡 Step-by-Step Explanation & Concept Rationale
Nickel catalyst facilitates addition of H2 across alkene double bonds in fatty acids.
Q. 18 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
Which gas is commonly known as 'Laughing Gas' in clinical anesthesia and propellant applications?
A
Dinitrogen Monoxide (Nitrous Oxide - N2O)
✓ Correct
B
Nitrogen Dioxide (NO2)
C
Nitric Oxide (NO)
D
Ammonia (NH3)
💡 Step-by-Step Explanation & Concept Rationale
N2O is an anesthetic and analgesic inhalation gas widely termed laughing gas.
Q. 19 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What is the primary chemical component of Plaster of Paris?
A
Calcium Sulfate Hemihydrate (CaSO4 . 1/2 H2O)
✓ Correct
B
Calcium Carbonate (CaCO3)
C
Calcium Hydroxide (Ca(OH)2)
D
Calcium Oxide (CaO)
💡 Step-by-Step Explanation & Concept Rationale
Plaster of Paris is produced by heating gypsum (CaSO4 . 2H2O) to form calcium sulfate hemihydrate.
Q. 20 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What functional group is characteristic of Carboxylic Acids, Esters, and Ketones respectively?
A
-COOH, -COOR, and -C(=O)-
✓ Correct
B
-CHO, -OH, and -NH2
C
-CONH2, -CN, and -SH
D
-O-, -X, and -NO2
💡 Step-by-Step Explanation & Concept Rationale
Carboxylic acids contain carboxyl (-COOH), esters contain alkoxycarbonyl (-COOR), and ketones contain carbonyl between carbons (-C(=O)-).
Q. 21 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What reagent is used to distinguish Aldehydes from Ketones via formation of a shiny silver mirror?
A
Tollens' Reagent (Ammoniacal Silver Nitrate)
✓ Correct
B
Benedict's Solution
C
Lucas Reagent
D
Fehling's Solution B
💡 Step-by-Step Explanation & Concept Rationale
Aldehydes reduce Tollens' reagent [Ag(NH3)2]+ to metallic silver (silver mirror), while ketones do not oxidize easily.
Q. 22 Chemistry (Secondary & College Level)
Difficulty: MEDIUM (1 Mark)
What test distinguishes primary, secondary, and tertiary alcohols based on the appearance of cloudiness with ZnCl2/HCl?
A
Lucas Test
✓ Correct
B
Biuret Test
C
Molisch Test
D
Iodoform Test
💡 Step-by-Step Explanation & Concept Rationale
Lucas reagent (anhydrous ZnCl2 in concentrated HCl) forms insoluble alkyl chloride immediately for tertiary alcohols, in 5 mins for secondary, and not at room temp for primary.
Q. 23 Chemistry (Secondary & College Level)
Difficulty: HARD (1 Mark)
What is the major organic product formed when Ethanol is dehydrated with concentrated H2SO4 at 170 °C?
A
Ethene (Ethylene - CH2=CH2)
✓ Correct
B
Diethyl ether (C2H5-O-C2H5)
C
Ethanoic acid
D
Ethyl hydrogen sulfate
💡 Step-by-Step Explanation & Concept Rationale
At 170 °C, concentrated sulfuric acid undergoes intramolecular elimination to form ethene. (At 140 °C, intermolecular dehydration yields diethyl ether).
Q. 24 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
Which law of chemical combination states that when elements combine, they do so in simple whole-number mass ratios?
A
Law of Definite Proportions (Proust's Law)
✓ Correct
B
Law of Conservation of Mass
C
Dalton's Law of Partial Pressures
D
Henry's Law
💡 Step-by-Step Explanation & Concept Rationale
Proust's law states that a chemical compound always contains exactly the same proportion of elements by mass.
Q. 25 Chemistry (Secondary & College Level)
Difficulty: EASY (1 Mark)
What is the oxidation state of Chromium in Potassium Dichromate (K2Cr2O7)?
A
+6
✓ Correct
B
+3
C
+7
D
+4
💡 Step-by-Step Explanation & Concept Rationale
In K2Cr2O7: 2(+1) + 2(Cr) + 7(-2) = 0 => 2Cr - 12 = 0 => Cr = +6.
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