List of top Questions asked in TN Board- 2026

What is Lanthanoid contraction? What are the causes and effects of Lanthanoid contraction?
Based on Valence bond theory, explain why the geometry of [Ni(CO)₄] is tetrahedral and [Ni(CN)₄]²- is square planar.
(a) (i) Differentiate crystalline solids and amorphous solids.
(ii) Explain the rate determining step with an example.
(a) (i) Differentiate crystalline solids and amorphous solids.
(ii) Explain the rate determining step with an example.
(a) (i) Explain the thermodynamics of cell reactions.
(ii) Why salt bridge is used in Galvanic cells?
Explain the mechanism of Cannizzaro reaction.
(i) How will you convert benzene diazonium chloride to biphenyl? Give the name of the reaction.
(ii) How will you confirm the presence of keto group at C-2 carbon in Fructose molecule?
Calculate the percentage efficiency of packing in case of body centered cubic (BCC) structure.
Prove that in case of first order reaction t₉₉.₉% = 10 t₁/₂
List any three characteristics of catalysts.
What are hormones? Give examples.
How is terylene prepared?
An organic compound (A) with molecular formula C₂H₇N reacts with nitrous acid to form compound (B) which is unstable. Hence compound (B) gets converted to compound (C). Compound (C) is used as a substitute for petrol. Identify compounds (A), (B) and (C).
(i) Write a short note on Gravity Separation process.
(ii) Sulphuric acid is a dehydrating agent. Explain with suitable examples.
(i) Give any three uses of silicones.
(ii) Write a short note on Fischer-Tropsch synthesis.
How will you convert phenol to phenolphthalein?
Give the tests for carboxylic acid group.
How do antiseptics differ from disinfectants?
Calculate the pH of 1.5 × 10⁻³ M solution of Ba(OH)₂.
Give the basic requirement for vapour phase refining.
Give the electronic configuration of Ce⁴⁺ and Co²⁺.
Which type of isomerism is exhibited by the following compounds? (a) [Co(NH₃)₄ Br₂]Cl and [Co(NH₃)₄ ClBr]Br
(b) [Co(NH₃)₅ NO₂]²⁺ and [Co(NH₃)₅ ONO]²⁺
(c) [Pt(NH₃)₄][PdCl₄] and [Pd(NH₃)₄][PtCl₄]
Propan-2-ol on reaction with anhydrous ZnCl₂ and concentrated HCl gives:
What is calcination? Give an example.
Mention the type of hybridisation in the following compounds:
(a) BrF₅ (b) BrF₃