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TN HSC 2026 Chemistry Answer Key Unofficial (OUT): Answer Key; Analysis

1. The stability of +1 oxidation state increases in the sequence
(a) In < Tl < Ga < Al
(b) Al < Ga < In < TI
(c) Ga < In < Al < TI
(d) Tl < In < Ga < Al

Answer: (b) Al < Ga < In < TI

4. Electrochemical process is used in the extraction of which of the following element?
(a) Sodium
(b) Iron
(c) Silver
(d) Lead

Answer: (a) Sodium

6. Which of the following statements is incorrect?
(a) Co³+ and Fe2+ have same number of unpaired electrons.
(b) Of all the known elements, Silver has the highest electrical conductivity at room temperature.
(c) To form a substitute alloy, the difference between the atomic radii of solvent and solute should be less than 15%.
(d) If the standard electrode potential (E°) of a metal is large and negative, the metal is a powerful oxidising agent.

Answer: (d) If the standard electrode potential (E°) of a metal is large and negative, the metal is a powerful oxidising agent.

7. Drugs that bind to the receptor site and inhibit its natural function are called
(a) enzymes
(b) antagonists
(c) molecular targets
(d) agonists

Answer: (b) antagonists

8. On which of the following properties does the coagulating power of an ion depend?
(a) The magnitude of the charge on the ion alone.
(b) Both magnitude and sign of the charge on the ion.
(c) The sign of charge on the ion alone.
(d) Size of the ion alone.

Answer: (b) Both magnitude and sign of the charge on the ion.

9. α-D(+) Glucose and B-D(+) Glucose are:
(a) Enantiomers
(b) Epimers
(c) Conformational isomers
(d) Anomers

Answer: (d) Anomers

11. The molar conductivity of a 0.5 mol dm ^-3 solution of AgNO ₃ with specific conductance 5.76×10 ^-3 Scm ^-1 at 298 K is:
(a) 0.086 Scm² mol ^-1
(b) 2.88 Scm² mol ^-1
(c) 28.8 Scm² mol ^-1
(d) 11.52 Scm² mol ^-1

^{Answer: (d) 11.52 Scm² mol -1}

12. Assertion: Due to Frenkel defect, density of the crystalline solid decreases.
Reason: In Frenkel defect, cation and anion leaves the crystal.
(a) Assertion is true but Reason is false.
(b) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(c) Both Assertion and Reason are false.
(d) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Answer: (c) Both Assertion and Reason are false.

14. How many geometrical isomers are possible for [Pt(Py) (NH3) (Br) (Cl)]?
(a) 0
(b) 3
(c) 15
(d) 4

Answer: (b) 3

15. Propan-2-ol on reaction with anhydrous ZnCl2 and concentrated HCl gives
(a) 1-chloropropane
(b) Ethyl chloride
(c) 2-chloro-2-methyl propane
(d) 2-chloropropane

Answer: (d) 2-chloropropane