List of top Chemistry Questions asked in PSEB XII

Define lanthanoid contraction.
Write down two similarities between lanthanoids and actinoids.
Transition elements or their compounds act as catalysts. Explain why.
Write down the following reactions: (a) Sandmeyer reaction (b) Hoffmann ammonolysis reaction (c) Wurtz–Fittig reaction (d) Finkelstein reaction (e) Friedel–Crafts alkylation
Complete the following reactions: (i) \(\ \text{CH}_3\text{OH} + \text{I}_2 + \text{NaOH} \xrightarrow{\Delta} \ ?\) (ii) \(\ \text{CH}_3\text{CH}_2\text{OH} \xrightarrow[\;523\,\text{K}\;]{\text{Al}_2\text{O}_3} \ ?\) (iii) \(\ \text{C}_2\text{H}_5\text{ONa} + \text{C}_2\text{H}_5\text{Br} \xrightarrow{\Delta} \ ?\)
Three electrolytic cells A, B and C containing electrolytes of zinc sulphate, silver nitrate and copper sulphate respectively were connected in series. A steady current of 1.5 A was passed through them until 1.45 g of silver were deposited at the cathode of cell B. (i) How long did the current flow? (ii) What weight of copper and zinc get deposited?
What is Lucas reagent? Write down Lucas test for distinction between primary, secondary and tertiary alcohols.
Starting from 100 g of a radioactive substance, 2.5 g was left after 5 years. If its radioactive decay follows first order kinetics, calculate: (i) Rate constant for the decay of the radioactive substance (ii) The amount of substance left after one year (iii) The time required for half of the substance to decay
Differentiate between fibrous and globular proteins.
Lower aliphatic amines are soluble in water. Why?
Write down a test to distinguish between aromatic primary amines and aliphatic primary amines.
Explain the mechanism of acidic dehydration of ethyl alcohol to form ethene.
Alkylamines are more basic than ammonia. Explain why?
Write down the following reactions: (i) Carbylamine reaction (ii) Reaction between benzene diazonium chloride and phenol in basic medium
Define coordination number.
How will you convert phenol to salicylaldehyde?
Write down the following reactions: (i) Aldol condensation (ii) HVZ reaction
Explain why carboxylic acids exist as associated molecules.
Consider the reaction: \[ 4\,\text{NO}_2(g) + \text{O}_2(g) \rightarrow 2\,\text{N}_2\text{O}_5(g) \] In an experiment, the rate of disappearance of O\(_2\) is \(0.24\,\text{mol L}^{-1}\text{s}^{-1}\). Calculate: (i) the rate of disappearance of NO\(_2\) and (ii) the rate of formation of N\(_2\)O\(_5\).
Write down the functions of a salt bridge in an electrochemical cell.
Calculate the number of molecules of oxalic acid \((\text{H}_2\text{C}_2\text{O}_4\cdot2\text{H}_2\text{O})\) in 100 mL of 0.2 N oxalic acid solution.
Define: (i) Half life of a reaction (ii) Pseudo first order reaction
Transition metals form alloys with other transition metals. Explain why?
Write down the IUPAC names of: (i) Na[PtBrCl(ONO)(NH\(_3\))] (ii) [Ag(NH\(_3\))\(_2\)][Ag(CN)\(_2\)]
Shazia removed the outer hard shells of two different eggs. She then placed one egg in pure water and the other egg in a saturated solution of sucrose. What change is she likely to observe in the eggs after a few hours? Explain it.