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Chemistry - 5 — MH-CET Full Length Paper MCQs with Solutions
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Sample questions with solutions
Q1 — easy
In a hexagonal close-packed (hcp) crystal lattice of identical rigid spheres, the coordination number of each sphere is:
A. 6
B. 8
C. 12 ✓ Correct
D. 4
Solution: In hcp, each sphere touches 6 in its own layer, 3 above, and 3 below: total coordination number = 12.
Q2 — easy
A solid has a cubic structure in which cation $X^+$ occupies all the 8 corners and anion $Y^-$ occupies the center of each face. The empirical formula of the crystal is:
A. $XY$
B. $XY_3$ ✓ Correct
C. $X_3Y$
D. $X_2Y_3$
Solution: Corners: $8 \times 1/8 = 1$ atom of $X$. Face-centres: $6 \times 1/2 = 3$ atoms of $Y$. Formula: $XY_3$.
Q3 — easy
In reverse osmosis water purification, the external pressure applied on the concentrated saline solution side must be:
A. Lower than atmospheric pressure
B. Equal to the osmotic pressure
C. Greater than the osmotic pressure ✓ Correct
D. Zero
Solution: Reverse osmosis occurs when external pressure greater than the osmotic pressure is applied, forcing solvent through the semi-permeable membrane against the concentration gradient.
Q4 — easy
The molal freezing point depression constant ($K_f$) of a solvent depends exclusively upon:
A. The nature of the solute
B. The nature of the solvent ✓ Correct
C. The concentration of the solution
D. The ambient atmospheric pressure
Solution: $K_f$ is a thermodynamic property of the solvent alone: $K_f = RT_f^2 M_{\text{solvent}}/(1000 \times \Delta H_{\text{fus}})$.
Q5 — easy
A solution containing $0.05\text{ M Ba(OH)}_2$ is completely dissociated at $298\text{ K}$. The pH of this solution is ($\log_{10} 1 = 0$):
A. 1.00
B. 13.00 ✓ Correct
C. 12.70
D. 13.30
Solution: $[\text{OH}^-] = 2 \times 0.05 = 0.1\text{ M}$. pOH $= 1.0$. pH $= 14 - 1 = 13.00$.
Q6 — easy
Which of the following salts undergoes cationic hydrolysis when dissolved in water, producing an acidic aqueous solution?
A. $\text{CH}_3\text{COONa}$
B. $\text{NH}_4\text{Cl}$ ✓ Correct
C. $\text{KNO}_3$
D. $\text{CH}_3\text{COONH}_4$
Solution: NH$_4$Cl is a salt of a weak base and a strong acid. The NH$_4^+$ cation undergoes hydrolysis, releasing H$^+$ ions and making the solution acidic.
Q7 — easy
For a reaction, both $\Delta H$ and $\Delta S$ are positive. The reaction will become spontaneous at:
A. Extremely low temperatures
B. High temperatures where $T > \frac{\Delta H}{\Delta S}$ ✓ Correct
C. All temperatures
D. No temperature
Solution: $\Delta G = \Delta H - T\Delta S$. With both positive, the reaction is spontaneous when $T\Delta S > \Delta H$, i.e., $T > \Delta H/\Delta S$.
Q8 — easy
In a dry cell (Leclanch\'e cell), the depolarizer surrounding the central graphite cathode consists of a paste of:
A. $\text{MnO}_2 + \text{carbon black}$ ✓ Correct
B. $\text{ZnCl}_2 + \text{KOH}$
C. $\text{PbO}_2 + \text{H}_2\text{SO}_4$
D. $\text{Ni(OH)}_2 + \text{Cd}$
Solution: In a Leclanch\'e dry cell, the cathode is a carbon rod embedded in a paste of MnO$_2$ mixed with powdered graphite (carbon black), which acts as the depolarizer.
Q9 — easy
The anomalous inertness and low thermal reactivity of nitrogen gas ($\text{N}_2$) at ambient room temperature is due to its:
A. Extremely high bond dissociation enthalpy ($941.4\text{ kJ/mol}$) ✓ Correct
B. Small atomic radius
C. High electronegativity
D. Presence of non-bonding lone pairs
Solution: N$_2$ has a triple bond with extremely high bond dissociation energy ($941.4\text{ kJ/mol}$), making it chemically inert under ordinary conditions.
Q10 — easy
Which of the following coordination complexes can exhibit optical isomerism (enantiomerism)?
A. $\text{cis-}[\text{Co}(\text{en})_2\text{Cl}_2]^+$ ✓ Correct
B. $\text{trans-}[\text{Co}(\text{en})_2\text{Cl}_2]^+$
C. $[\text{Pt}(\text{NH}_3)_2\text{Cl}_2]$
D. $[\text{Co}(\text{NH}_3)_4\text{Cl}_2]^+$
Solution: cis-$[\text{Co}(\text{en})_2\text{Cl}_2]^+$ lacks any plane or centre of symmetry, allowing non-superimposable mirror images (enantiomers). The trans-isomer has a plane of symmetry.
Q11 — easy
When propene is treated with $N$-bromosuccinimide (NBS) in carbon tetrachloride under ultraviolet irradiation, the major product is:
A. 1-Bromopropene
B. 2-Bromopropene
C. 3-Bromopropene (Allyl bromide) ✓ Correct
D. 1,2-Dibromopropane
Solution: NBS selectively abstracts an allylic hydrogen from propene to produce a resonance-stabilized allyl radical, yielding 3-bromopropene (allyl bromide).
Q12 — easy
In an $\text{S}_\text{N}2$ substitution of an optically active $(R)$-2-bromobutane with aqueous hydroxide ion ($\text{OH}^-$), the resulting butan-2-ol product displays:
A. Complete retention of configuration
B. Complete inversion of configuration (Walden inversion) ✓ Correct
C. Partial racemization ($50\% d + 50\% l$)
D. Formation of a meso compound
Solution: In S$_N$2, backside nucleophilic attack occurs simultaneously with leaving group departure, inverting the configuration completely (Walden inversion).
Q13 — easy
Heating phenyl acetate with anhydrous aluminum chloride ($\text{AlCl}_3$) undergoes an intramolecular acyl migration to yield $o$- and $p$-hydroxyacetophenone. This reaction is known as:
A. Claisen rearrangement
B. Fries rearrangement ✓ Correct
C. Kolbe reaction
D. Reimer-Tiemann reaction
Solution: Fries rearrangement is the Lewis-acid-catalyzed conversion of a phenolic ester into ortho- and para-hydroxyaryl ketones.
Q14 — easy
The distinguishing chemical test to differentiate between primary, secondary, and tertiary alcohols using a mixture of concentrated $\text{HCl}$ and anhydrous $\text{ZnCl}_2$ is known as:
A. Victor Meyer test
B. Lucas test ✓ Correct
C. Baudisch test
D. Hinsberg test
Solution: Lucas reagent (conc. HCl + anh. ZnCl$_2$) distinguishes alcohols: tertiary reacts immediately, secondary in ~5 min, primary shows no turbidity at room temperature.
Q15 — easy
Treatment of an aldehyde with hydrogen cyanide ($\text{HCN}$) in the presence of a trace of base produces a cyanohydrin. The nucleophile in this reaction is:
A. $\text{H}^+$
B. $\text{CN}^-$ ✓ Correct
C. $\text{HCN}$
D. $\text{OH}^-$
Solution: The base generates the cyanide anion ($\text{CN}^-$), which serves as the active nucleophile attacking the electrophilic carbonyl carbon.
Q16 — easy
Carboxylic acids have significantly higher boiling points than alcohols of comparable molecular mass because carboxylic acids:
A. Have higher dipole moments
B. Form stable cyclic dimers held by two intermolecular hydrogen bonds ✓ Correct
C. Undergo intramolecular hydrogen bonding
D. Are stronger acids
Solution: Carboxylic acid molecules associate into cyclic dimers held by two complementary intermolecular hydrogen bonds, raising boiling points significantly above those of alcohols.
Q17 — easy
Reaction of benzoic acid with thionyl chloride ($\text{SOCl}_2$) in dry pyridine yields:
A. Benzoyl chloride ✓ Correct
B. Benzyl chloride
C. Chlorobenzene
D. Benzamide
Solution: $\text{C}_6\text{H}_5\text{COOH} + \text{SOCl}_2 \to \text{C}_6\text{H}_5\text{COCl} + \text{SO}_2 + \text{HCl}$. Gaseous by-products escape, driving the reaction forward.
Q18 — easy
When primary amine is treated with benzenesulfonyl chloride (Hinsberg reagent) in excess aqueous $\text{KOH}$, the resulting product:
A. Precipitates out and is insoluble in alkali
B. Dissolves to form a clear water-soluble potassium salt ✓ Correct
C. Explodes violently
D. Releases nitrogen gas
Solution: Primary amines form $N$-alkylbenzenesulfonamide. The N-H is acidic (due to electron-withdrawing sulfonyl group) and dissolves readily in aqueous KOH to form a soluble salt.
Q19 — easy
Azo dye test involves coupling of a freshly prepared benzene diazonium chloride solution with alkaline $\beta$-naphthol to produce an intense:
A. Canary yellow precipitate
B. Scarlet red/orange dye ✓ Correct
C. Deep royal blue solution
D. Emerald green precipitate
Solution: Diazonium chloride couples electrophilically with alkaline $\beta$-naphthol to precipitate an orange-red insoluble azo dye.
Q20 — easy
The cyclic six-membered pyranose ring structure of D-(+)-glucose involves an intramolecular hemiacetal linkage between:
A. $\text{C}_1$-OH and $\text{C}_4$
B. $\text{C}_1$-CHO and $\text{C}_5$-OH ✓ Correct
C. $\text{C}_2$-C=O and $\text{C}_5$-OH
D. $\text{C}_1$-CHO and $\text{C}_6$-OH
Solution: Cyclization occurs when the nucleophilic OH at C$_5$ attacks the electrophilic carbonyl carbon at C$_1$, forming a six-membered pyranose hemiacetal ring.
Q21 — easy
The non-protein organic or inorganic chemical component required for the biological catalytic activity of a conjugated enzyme is known as a:
A. Apoenzyme
B. Cofactor (or Coenzyme) ✓ Correct
C. Zymogen
D. Substrate
Solution: A holoenzyme = apoenzyme (protein) + cofactor/coenzyme (non-protein component like NAD$^+$, FAD, or metal ions).
Q22 — easy
Which of the following statements about RNA is chemically INCORRECT?
A. The pentose sugar present is $\beta$-D-ribose
B. It contains uracil instead of thymine
C. It possesses a double-stranded helical structure identical to B-DNA in all organisms ✓ Correct
D. It is directly involved in protein biosynthesis
Solution: Unlike double-stranded B-DNA, RNA molecules exist predominantly as single-stranded polynucleotide chains folded into complex tertiary structures.
Q23 — easy
Glyptal is an alkyd polyester resin manufactured by the polycondensation of ethylene glycol with:
A. Phthalic acid (or phthalic anhydride) ✓ Correct
B. Terephthalic acid
C. Adipic acid
D. Maleic anhydride
Solution: Glyptal is formed by condensation polymerization of ethylene glycol with phthalic acid (or phthalic anhydride).
Q24 — easy
During free-radical addition polymerization of ethene to form low-density polythene (LDPE), the chemical species acting as the initiator is:
A. Benzoyl peroxide ✓ Correct
B. Titanium tetrachloride
C. Triethylaluminum
D. Concentrated sulfuric acid
Solution: LDPE is manufactured using organic peroxides like benzoyl peroxide (or trace oxygen) as a free-radical chain initiator at high pressures and temperatures.
Q25 — easy
Which of the following biodegradable polymers is a polyamide copolymer synthesized from glycine and $\epsilon$-aminocaproic acid?
A. PHBV
B. Nylon-2-nylon-6 ✓ Correct
C. Nylon-6
D. PGA
Solution: Nylon-2-nylon-6 is an alternating biodegradable polyamide copolymer from glycine (2 carbons) and $\epsilon$-aminocaproic acid (6 carbons).
Q26 — easy
The 12th principle of Green Chemistry, "Inherently Safer Chemistry for Accident Prevention", aims primarily at:
A. Using renewable raw feedstocks exclusively
B. Minimizing the potential for chemical accidents, explosions, releases, and fires ✓ Correct
C. Maximizing the atom economy to 100%
D. Avoiding the use of biocatalysts
Solution: Principle 12 states that chemical substances and their forms should be chosen to minimize the likelihood of chemical accidents, including toxic releases, fires, and explosions.
Q27 — easy
A gaseous hydrocarbon contains $80\%$ carbon and $20\%$ hydrogen by mass. If its vapour density is 15, its molecular formula is:
A. $\text{CH}_4$
B. $\text{C}_2\text{H}_6$ ✓ Correct
C. $\text{C}_2\text{H}_4$
D. $\text{C}_3\text{H}_8$
Solution: C: $80/12 = 6.67$, H: $20/1 = 20$. Ratio $1:3$, empirical formula CH$_3$ (mass 15). Molecular mass $= 2 \times 15 = 30$. Factor $= 30/15 = 2$. Formula: C$_2$H$_6$.
Q28 — easy
The wavelength of a matter wave associated with a bowling ball of mass $0.663\text{ kg}$ moving at a velocity of $100\text{ m/s}$ is ($h = 6.63 \times 10^{-34}\text{ J}\cdot\text{s}$):
A. $1.0 \times 10^{-35}\text{ m}$ ✓ Correct
B. $1.0 \times 10^{-33}\text{ m}$
C. $6.63 \times 10^{-34}\text{ m}$
D. $1.0 \times 10^{-31}\text{ m}$
Solution: $\lambda = h/(mv) = 6.63 \times 10^{-34}/(0.663 \times 100) = 6.63 \times 10^{-34}/66.3 = 1.0 \times 10^{-35}\text{ m}$.
Q29 — easy
Beryllium differs anomalously from other alkaline earth metals and exhibits diagonal relationship with aluminum due to its:
A. Large atomic size and low electronegativity
B. Small ionic size and high polarizing power (charge/radius$^2$) ✓ Correct
C. High electropositive character
D. Inability to form covalent bonds
Solution: Be$^{2+}$ has very small ionic radius (31 pm), giving exceptionally high charge-to-size ratio and polarizing power comparable to Al$^{3+}$.
Q30 — easy
At the critical temperature ($T_c$) of a real gas, the meniscus separating liquid and vapour phases:
A. Becomes completely sharp and opaque
B. Disappears entirely as densities become equal ✓ Correct
C. Freezes into a polycrystalline solid
D. Shows rapid boiling with violent bubbling
Solution: At the critical point, the density of the saturated liquid equals the density of the saturated vapour; the physical meniscus boundary vanishes completely.