List of top Questions asked in UP Board XII

Which type of isomerism exists between the complexes [CoBr(NH₃)₅]SO₄ and [CoSO₄(NH₃)₅]Br?

Which of the following ions forms coloured solution?

α-D(+)glucose and β-D(+)glucose are

The reagent which does NOT react with both acetone and benzaldehyde is

When aniline is heated with CHCl₃ in the presence of KOH, the product formed is

Read the following assertion and reason and choose the correct alternative.
Assertion: Osmotic pressure is a colligative property.
Reason: Osmotic pressure is directly proportional to molarity at a given temperature.

Write four characteristics of transition elements.

How would you convert:
i) Ethanoic acid to methanamine? (1)
ii) Aniline to 2,4,6-tribromoaniline? (1)
iii) Aniline to benzene diazonium chloride? (1)
iv) Aniline to phenyl isocyanide? (1)
v) Chlorobenzene to chlorobenzene sulphonic acid? (1)
OR
i) Write four chemical equations for the methods of preparation of aniline. (1+1+1+1)
ii) Write the chemical equation of any one method for the preparation of chlorobenzene. (1)

What are nucleic acids? Explain the difference between DNA and RNA and state their two important biological functions.
OR
How can vitamins be classified? Write the name of a fat soluble vitamin. Which vitamin is responsible for blood clotting?

If 2 g of benzoic acid is dissolved in 25 g of benzene, its depression in freezing point was found to be 1.62 K. Molal depression constant of benzene is 4.9 K kg mol^-1. If benzoic acid forms a dimer in this solution, what will be the percentage association of benzoic acid? (5)
OR
A 200 cm³ aqueous solution of a protein contains 1.26 g of protein. The osmotic pressure of this solution at 300 K is \(2.57\times10^{-3}\) bar. Calculate the molar mass of this protein. (5)

Write the product of the following reactions along with their mechanism:
i) p-nitrochlorobenzene + NaOH (623 K, 300 atm), then H⁺ → [A]
ii) Chlorobenzene + CH₃COCl (anhydrous AlCl₃) → [B] + [C]
iii) CH₃–CH=C(CH₃)₂ + HBr → [D]
OR
Write short notes on the following: i) D.D.T. ii) Freon iii) Carbon tetrachloride

Identify the product of the following reactions:
i) cyclopentanone \(+\) \(HO-NH_2 \xrightarrow{H^+}\) [A] (1)
ii) cyclohexanone \(+\) 2,4-dinitrophenylhydrazine \((H_2N-NH-C_6H_3(NO_2)_2) \rightarrow\) [B] (1)
iii) benzene-1,2-dicarboxylic acid (phthalic acid) \(+\) \(NH_3 \rightarrow\) [A] \(\xrightarrow[-H_2O]{\Delta}\) [B] (2)

i) Explain the Hell-Volhard-Zelinsky reaction with example. (2)
ii) Explain the Hofmann bromamide degradation reaction with example. (2)

Write the IUPAC names of the following coordination compounds:
i) \([Pt(NH_3)_2ClNO_2]\)
ii) \([Co(NH_3)_5(CO_3)]Cl\)
iii) \([Ni(CO)_4]\)
iv) \([Co(NH_3)_5ONO]^{2+}\) (1+1+1+1)

Differentiate between primary, secondary and tertiary alcohols, showing their structure. In the presence of which enzyme does glucose convert to ethyl alcohol? (3+1)

Explain, giving reasons:
i) Transition metals and most of their compounds are paramagnetic.
ii) Transition metals generally form coloured compounds.

For the first-order reaction \(N_2O_5(g) \rightarrow 2NO_2(g) + O_2(g)\), the initial concentration of \(N_2O_5\) at 318 K was \(1.24 \times 10^{-2}\) mol L^-1, which decreased to \(0.20 \times 10^{-2}\) mol L^-1 after 60 minutes. Calculate the rate constant at 318 K.

Define conductivity and molar conductivity of an electrolyte solution. Discuss the change in their value with the change in concentration of electrolyte.

A 200 cm³ aqueous solution of a protein contains 1.26 g of protein. The osmotic pressure at 300 K was found to be \(2.57 \times 10^{-3}\) bar. Calculate the molar mass of the protein. (R = 0.083 L bar K^-1 mol^-1)

The two strands of DNA are not identical, but complementary to each other. Explain.

Write the Nernst equation and also explain the relation between electrode potential \( (E_{cell}) \) and the equilibrium constant \( (K_c) \).

Write the reason of the following: Ethylamine is soluble in water, while aniline is not soluble in water.

[NiCl₄]^2- is paramagnetic, while Ni(CO)₄ is diamagnetic, although both are tetrahedral. Why?

How will you prepare phenol from the following reagents (write only chemical equation)?
i) Benzene
ii) Aniline

Unit of rate constant of a first order reaction is —