UP Board Class 12 Chemistry Question Paper with Answer Key (March 4, Code 347 CD)

Molarity of pure water is:

• (A) 5.556 mol L\(^{-1}\)
• (B) 55.56 mol L\(^{-1}\)
• (C) 0.18 mol L\(^{-1}\)
• (D) 81.00 mol L\(^{-1}\)

Unit of specific conductance is:

• (A) cm\(^{-2}\) ohm\(^{-1}\)
• (B) cm ohm\(^{-1}\) eq\(^{-1}\)
• (C) cm\(^{-1}\) ohm\(^{-1}\)
• (D) cm\(^{-2}\) ohm

Noble gas which forms maximum number of compounds is:

• (A) Ne
• (B) Xe
• (C) Ar
• (D) He

Formation of coloured ions is possible due to the presence of:

• (A) unpaired electrons
• (B) paired electrons
• (C) non-bonded electrons
• (D) None of the above

Reaction RCOOAg \(\xrightarrow{Br_{2}/CCl_{4}}\) RBr is called:

• (A) Hunsdiecker reaction
• (B) Schmidt reaction
• (C) *****-Volhard-Zelinsky reaction
• (D) Tishchenko reaction

Amino acids are structural units of:

• (A) carbohydrates
• (B) proteins
• (C) lipids
• (D) vitamins

Silver crystallises in f.c.c. lattice. If edge length of the cell is \(4.077 \times 10^{-8}\) cm and density is \(10.5 \, gm cm^{-3}\), calculate the atomic mass of silver.

Calculate the mass of a non-volatile solute (molar mass \(40 \, gm mol^{-1}\)) which should be dissolved in \(114 \, gm\) octane to reduce its vapour pressure to 80%.

Calculate the standard e.m.f. of the following cell:

Zn \(\mid\) Zn\(^{2+}\) \(\parallel\) Cu\(^{2+}\) \(\mid\) Cu

Given: \(E^\circ_{(Zn^{2+}/Zn)} = -0.76 \, V\) and \(E^\circ_{(Cu^{2+}/Cu)} = +0.34 \, V\)

Differentiate between lyophilic and lyophobic colloids.

What is Kohlrausch’s law? Write its one application with example.

Give any two dehydrating properties of H\(_2\)SO\(_4\).

1 : 1 Molar mixture of FeSO\(_4\) and (NH\(_4\))\(_2\)SO\(_4\) gives test of Fe\(^{2+}\) ions, but 1 : 4 molar mixture of CuSO\(_4\) and NH\(_3\) (aq) does not give test of Cu\(^{2+}\) ions. Why?

Ketones do not reduce Fehling’s solution and Tollen’s reagent, while fructose containing ketonic group does. Why?

Classify each of the following solids as ionic, metallic and molecular: P\(_4\), Ammonium phosphate, Brass, Tetraphosphorus decoxide (P\(_4\)O\(_{10}\)), Rb, I\(_2\), LiBr

Explain with reason:

• (i) The colloidal solution of Fe(OH)\(_3\) obtained from FeCl\(_3\) is positively charged.
• (ii) Alum is used for the purification of water.
• (iii) Rivers form a delta while joining a sea/ocean.

Answer the following:

• (i) How do the atomic radii of transition metals vary across a series and why?
• (ii) Ions of transition metals are generally paramagnetic. Why?
• (iii) Transition elements show different oxidation states. Why?

Prove the presence of five –OH groups and a –CHO group in glucose molecule, giving chemical equations. How is silver mirror formed from glucose?

Differentiate between molar and molal elevation constants. Give two different formulae involving these two constants for the determination of molecular mass of solute.

Describe Ostwald’s process for the manufacture of nitric acid. How will you detect NO\(_3^-\) radical in this acid? Give equations for reactions involved.

Using IUPAC norms, write the systematic names of the following:

• (i) [Co(NH\(_3\))\(_6\)]Cl\(_3\)
• (ii) K\(_3\)[Cr(C\(_2\)O\(_4\))\(_3\)]:
• (iii) [Pt(NH\(_3\))\(_2\)Cl\(_2\)]:
• (iv) [Ni(CO)\(_4\)]:

An aromatic organic compound A on treatment with aqueous ammonia and heating forms compound B, which on heating with Br\(_2\) and KOH forms a compound C of molecular formula C\(_6\)H\(_7\)N. Write the structures and names of compounds A, B and C.

An aromatic organic compound A yields B and C when it reacts with CHCl\(_3\) and KOH. On distillation with Zn dust, D is formed. On oxidation, D yields compound E having molecular formula C\(_7\)H\(_6\)O\(_2\). Identify A, B, C, D and E. Write the chemical equation of each reaction also.

Write short notes on:

• (i) Williamson’s ether synthesis
• (ii) Fermentation
• (iii) To obtain methyl alcohol from pyroligneous acid

For the reaction 2A + B \(\longrightarrow\) 2C + 3D, the rate of change in concentration of C is 1.0 mol L\(^{-1}\) s\(^{-1}\). Find the rate of reaction and rate of change in concentration of A, B and D.

In the reaction 2A \(\longrightarrow\) Products, concentration of A decreases from 0.5 mol L\(^{-1}\) to 0.4 mol L\(^{-1}\) in 10 minutes. Find the rate of reaction during the time interval.

For the reaction \(N_2O_5 \longrightarrow 2NO_2 + \tfrac{1}{2}O_2\), if
\[ -\frac{d[N_2O_5]}{dt} = K'[N_2O_5], \quad \frac{d[NO_2]}{dt} = K''[N_2O_5], \quad \frac{d[O_2]}{dt} = K'''[N_2O_5] \]

then establish the relation between \(K'\), \(K''\), and \(K'''\).

A reaction is of first order with respect to a reactant. How is the rate of reaction affected, if the concentration of the reactant is doubled?

What happens when (Write chemical equations only):

• (i) n-Butyl chloride reacts with alcoholic KOH?
• (ii) Bromobenzene reacts with magnesium in the presence of dry ether?
• (iii) Ethyl chloride reacts with aqueous KOH?
• (iv) Methyl bromide reacts with sodium in the presence of dry ether?
• (v) Ethyl bromide reacts with KCN (alc.)?

How will you convert chlorobenzene into the following? (Write chemical equations only)

• (i) Benzene
• (ii) Phenol
• (iii) Toluene
• (iv) Aniline
• (v) Diphenyl

77% Carbon, 11.63% Hydrogen and the rest Oxygen is present in an organic compound. The molecular mass of the compound is 86. The compound does not reduce Tollen’s reagent but gives an addition compound with sodium hydrogen sulphite and gives positive iodoform test. On strong oxidation it gives ethanoic acid and propanoic acid. Write the structure of possible compound.

Write short notes on the following:

• (i) Claisen Reaction
• (ii) Cannizzaro’s Reaction
• (iii) Rosenmund’s Reaction