List of top Questions asked in UP Board XII

In which cell does the following reaction take place? \[2H_2(g) + O_2(g) \rightarrow 2H_2O(l)\]

The most active metal among the following is:

The order of reaction for which the unit of the velocity (rate) constant is \(mol\,L^{-1}\,s^{-1}\) is:

Which of the following solutions will have a maximum boiling point?

(i) Explain Hinsberg test for the distinction between primary, secondary and tertiary amines. (ii) Write a short note on Carbylamine reaction. (2½+2½=5)
OR
What happens when (write chemical equations only): (i) Aqueous solution of benzene diazonium chloride is heated (ii) Acetamide is reacted with aqueous KOH in the presence of bromine (iii) Aniline reacts with sodium nitrite and dil. HCl at 0°C (iv) Aniline reacts with acetic anhydride in the presence of pyridine (v) Aniline reacts with Bromine water. (1+1+1+1+1=5)

Write short notes on the following. (i) Cross aldol condensation (ii) Stephen reaction (iii) Etard reaction. (2+1½+1½=5)
OR
How will you obtain (write chemical equations only): (i) Ethanoic anhydride from Ethanoic acid (ii) Benzoic acid from Ethyl benzoate (iii) Benzamide from benzoic acid. (2+1½+1½=5)

(i) Write notes on Williamson's synthesis. (ii) Write the chemical equation for the preparation of phenol from cumene. (iii) How will you convert phenol to salicylaldehyde? (2+1½+1½=5)
OR
What happens when (write chemical equations only): (i) Phenol reacts with dil. HNO₃ (ii) Ethyl methyl ether is heated with conc. HI (iii) Phenol is heated with conc. HNO₃ in the presence of conc. H₂SO₄ (iv) Ethyl alcohol reacts with thionyl chloride in the presence of pyridine (v) Phenol reacts with bromine water. (1+1+1+1+1=5)

Write short notes on the following: (i) Freons (ii) Sandmeyer reaction (iii) Friedel Craft acylation of haloarene. (2+1½+1½=5)
OR
What happens when (write chemical equation only): (i) Propene reacts with HI (ii) Ethyl bromide reacts with magnesium in the presence of dry ether (iii) Chlorobenzene is heated with sodium in dry ether (iv) The mixture of chlorobenzene and methyl chloride is heated with sodium in the presence of dry ether (v) Isopropyl alcohol reacts with conc. HCl and ZnCl₂. (1+1+1+1+1=5)

Discuss the chelate effect with an example. Explain the nature of bonding in \( [\text{Fe}(\text{CN})_6]^{4-} \) on the basis of valence bond theory. (2+2=4)

Write the Nernst equation of the following cell at 298 K and calculate its electromotive force.
\( \text{Mg(s)} \mid \text{Mg}^{2+}\,(0.001\,M) \parallel \text{Cu}^{2+}\,(0.0001\,M) \mid \text{Cu(s)} \)
Given: \( E^\circ_{Mg^{2+}/Mg} = -2.37\,V \) and \( E^\circ_{Cu^{2+}/Cu} = 0.34\,V \). (4)

What is the order of reaction? Derive the integrated rate equation for a first order reaction and obtain an expression for the half life period of this reaction. (1+2+1=4)

(i) Write a short note on the cyclic structure of glucose.
(ii) What is the difference between a nucleoside and a nucleotide? (2+2=4)

An aqueous solution of glucose is 10% (w/w). What would be the molality and mole fraction of each component in the solution? (Molar mass of glucose = 180 g mol⁻¹)

Define molar conductivity of a solution of an electrolyte and explain Kohlrausch law.

Describe the effect of concentration and temperature on the rate of chemical reaction. Rate constant K = 5.5 × 10⁻¹⁴ s⁻¹ for a first order reaction. Calculate the half life time of this reaction.

(i) Explain with reason that transition metals generally form coloured compounds.
(ii) Write a short note on the lanthanoid contraction.

How will you differentiate the following?
(i) Acetaldehyde and acetone
(ii) Acetaldehyde and formaldehyde

Differentiate between fibrous and globular proteins.

Explain reverse osmosis and write any one example of artificial semipermeable membrane. (1+1=2)

Alkyl chloride reacts with aqueous KOH to form alcohol while in the presence of alcoholic KOH, alkene is obtained as major product. Explain. (2)

Write the IUPAC names of the following coordination compounds.
(i) \( [Cr(NH_3)_2Cl_2(en)]Cl \)
(ii) \( [Pt(NH_3)_4Cl_2][PtCl_4] \) (1+1=2)

Ortho nitrophenol is more acidic than phenol. Explain. Draw the resonance structures of their corresponding phenoxide ion. (2)

Mention the different steps for the preparation of potassium permanganate from pyrolusite ore and draw the structure of permanganate ion. (1+1=2)

Define molal elevation constant. (2)

Benzyl alcohol is obtained from benzaldehyde by the following reaction.