List of top Questions asked in UP Board XII

The resistance of a conductivity cell filled with 0.1 mol L\(^{-1}\) KCl solution is 100 \( \Omega \). If the resistance of the same cell when filled with 0.02 mol L\(^{-1}\) KCl solution is 520 \( \Omega \), find the conductivity and molar conductivity of the 0.02 mol L\(^{-1}\) KCl solution. The conductivity of a 0.1 mol L\(^{-1}\) KCl solution is 1.29 S/m.

The rate constant for a first order reaction is 60 sec\(^{-1}\). How much time will it take for the reactant to reduce to 1/16th of its initial concentration?

Which of the following is the mathematical form of Raoult's law?

The number of unpaired electrons in \( Cu^{2+} \) is

Formaldehyde reacts with KOH to give methanol and potassium formate. What is the name of the reaction?

Chloroform is oxidised in the presence of sunlight to form

Glucose does not react with which of the following?

Explain mole fraction. Calculate the mole fraction of ethylene glycol if 20% of the mass of ethylene glycol is present in the solution. [1+4]
OR
i) Calculate the molarity of the solution in which 5 g NaOH is dissolved in 450 mL of solution.
ii) Calculate the molality of the solution in which 2.5 g acetic acid is dissolved in 75 g benzene. [2½+2½]

Discuss the nature of bonding in \( [CoF_6]^{3-} \) and \( [Ni(CN)_4]^{2-} \) on the basis of valence bond theory (VBT) and find the value of magnetic moment in both.

OR
Explain the stereoisomerism in coordination compounds with suitable examples.

i) Write the chemical names of water soluble vitamins and the diseases caused by their deficiency.
ii) Explain the cyclic structure of glucose. [2+3]
OR
i) Explain the primary, secondary, tertiary and quaternary structures of protein.
ii) Write a note on denaturation of protein. [4+1]

Complete the following reactions:
i) \( C_6H_5COCl \xrightarrow{H_2 / Pd\text{-}BaSO_4} ? \)
ii) \( CH_3\text{-}CO\text{-}CH_2\text{-}CO\text{-}OC_2H_5 \xrightarrow{(i)\ NaBH_4\ (ii)\ H^+} ? \)
iii) anisole \( (C_6H_5OCH_3) + CH_3COCl \xrightarrow{anhydrous\ AlCl_3} ? \)
iv) acetophenone \( (C_6H_5COCH_3) + NaOH + I_2 \rightarrow \) ......
v) \( CH_3CHO + Zn\text{-}Hg + HCl \rightarrow \) ......

OR
Write short notes on the following:
i) Tollen's test
ii) Fehling test
iii) Haloform reaction of methyl ketone
iv) Reaction of phenyl methyl ketone with 2,4-dinitrophenyl hydrazine (2,4-DNP)
v) Wolff-Kishner reaction.

What are fuel cells? Draw a labelled diagram of the hydrogen–oxygen fuel cell and give the reactions that occur in the cell.

Write the reagent for each of the following reactions:
i) R–OH + …… → R–Cl
ii) R–OH + …… → R–Br
iii) CH₂=CH₂ + …… → BrCH₂–CH₂Br
iv) C₆H₅–CH=CH₂ + …… → C₆H₅–CH₂–CH₂Br

Write a method of preparation of diethyl ether and write the mechanism of the reaction of diethyl ether with HI.

Explain molecularity and order of a reaction with the help of an example.

Write the structure of (A), (B) and (C) in the following reaction: phenol (C₆H₅OH) with concentrated HNO₃ gives (C); phenol with dilute HNO₃ gives (A) + (B).

i) Write the electronic configuration of an element with atomic number 24.
ii) Find the number of unpaired electrons in the Co²⁺ ion.
iii) Why is the range of oxidation states in the actinoid series greater than in the lanthanoid series?

Write the structure of (A), (B) and (C) in the following reaction:
\[ C_6H_5NO_2 \xrightarrow{Fe/HCl} (A) \xrightarrow{NaNO_2 + HCl,\ 273\,K} (B) \xrightarrow{H_2O/H^+,\ \Delta} (C) \]

What happens when aniline reacts with the following?
i) Bromine water
ii) (CH₃CO)₂O / Pyridine
iii) HNO₂ + HCl (0°-5°C)

Why do the transition metals and many of their compounds act as catalysts? Explain.

Write the mechanism of the bimolecular nucleophilic substitution reaction (S_N2) of an alkyl halide.

What is the van't Hoff factor? Write the equation for colligative properties including the van't Hoff factor.

Give the IUPAC names of the following organic compounds:
i) \( CH_3-CH_2-CO-CH_2-CH(CH_3)-CH_3 \)
ii) \( C_6H_5-CH=CH-CHO \)

\( [NiCl_4]^{2-} \) is paramagnetic, while \( [Ni(CO)_4] \) is diamagnetic although both are tetrahedral. Why?

Define electrode potential and emf of a cell.