Class 12 Chemistry

What is the molarity of 0.4 N \( Na_2CO_3 \)solution?

A) 0.1 M        B) 0.2 M        C) 0.4 M         D) 0.8 M

Normality and molarity are the terminologies of volumetric analysis used to express the concentration of solution.

i) Distinguish between molarity and normality. 

 ii) Deduce the normality equation \( S_1V_1 = S_2V_2 \). 

iii) Why is this equation not always used to calculate molarity? 

 iv) Your chemistry teacher added 4gm of sodium hydroxide in a bottle containing 20 CC of 2N \( H_2SO_4 \) and he diluted it up to 1 litre by adding water. Then, he gave you a blue and a red litmus paper.

a) Which litmus paper would you used to test the solution and why?  

b) Calculate the normality of the dilute solution. 

   OR 

In a following given reaction:

\( SO_3 + 3H_2S \rightarrow 3H_2O + 4S \)

a) Express the rate of above reaction in term of reactants and products. 

 b) The concentration of \( H_2S \) decreased by $0.06 mol/litre$ in 2 second. 

 i) Calculate the rate of formation of Sulphur.

 ii) Why is rate of formation of water is not equal to the rate of disappearance of \( SO_3 \)? 

iii) Calculate the rate of disappearance of \( SO_3 \)

 c) Draw an energy profile diagram to illustrate the effect of catalyst on the activation energy hence on rate. 

d) Define energy of activation. 

What is the normality of\( 5\% \text{Na}_2\text{CO}_3 \) solution?

 A) \( 0.94\text{ N} \)    B) \( 0.98\text{ N} \)    C) \( 0.99\text{ N} \)      D)\( 1.01\text{ N} \)

a) Write any two differences between primary standard and secondary standard substance. 

b) \( 3.15 \text{ g} \) of oxalic acid crystal\( (\text{C}_2\text{H}_2\text{O}_4 \cdot 2\text{H}_2\text{O}) \) was dissolved in water to make \( 500 \text{ mL} \) of its solution.

i) Determine the normality of the acid. 

 ii) The acid solution became permanently pink when \( 400 \text{ mL} \) of \( \text{KMnO}_4 \) solution (\( \text{eq.wt.} = 31.5 \)) was added during titration. What mass of the \( \text{KMnO}_4 \) is present in 1 liter of the solution? 

Which of the following will have highest pH in water solution?

A) NaCl        B) \( Na_2CO_3 \)     C) KCl             D) \( CuSO_4 \)

Define the following terms.

i) Lewis base

ii) Basic buffer 

Calculate the pH of solution obtained by mixing equal volumes of two solutions having pH=3 and pH=5. 

a) Distinguish between pseudo first order and first order reaction giving an example of each.

b) Draw an energy profile diagram showing energy of activation for endothermic reaction.

c) The hypothetical data for the reaction,\(  2A + B \rightarrow C \), are:

Calculate the rate of formation of 'C' when the concentration of 'A' and 'B' are \( [0.6]\text{ molL}^{-1} \) and \( (0.3)\text{ molL}^{-1} \) respectively. 

        OR 

a) Deduce normality equation. 

b) Give reason.

i) Methyl orange is used as indicator for the titration between \( H_2SO_4 \) and \( Na_2CO_3 \) 

ii) Oxalic acid solution is warmed by adding \( dil. H_2SO_4 \) before titration with \( KMnO_4 \)

c) 0.70 g of a sample of \( Na_2CO_3 \cdot xH_2O \) was dissolved in water and volume was made 100 ml. 20 ml of this solution required 19.8 ml of \( \frac{N}{10}\ HCl \) for complete neutralization. Find the value of x. 

1. An aqueous solution having \( P^H = 0 \) is

A) acidic   (B) basic      (C) neutral       (D) amphoteric

Which of the following is the ionic product of water at \( 393\text{ K} \)?

A) Greater than \( 1 \times 10^{-14} \)     B) Less than \( 1 \times 10^{-14} \)

C) Equal to\( 1 \times 10^{-14} \)             D) Equal to \( 1 \times 10^{-7} \)

. The rate constant of a reaction is \( 21 \times 10^{-2} \ mol^{-2} \cdot lit^2 min^{-1} \) The order of the reaction is 

 (A) zero      (B) first       (C) second      (D) third

Which order of reaction does the following chemical equation represent? \( \text{RCOOR} + \text{H}_2\text{O} \xrightarrow{\text{H}^+} \text{RCOOH} + \text{ROH} \)

A) Zero order     B) Pseudo-first order     C) Second order    D) Third order

a) Write any two differences between order and molecularity of a reaction. 

 b) Draw a graph showing the relationship between concentration of reactant and time for a zero order reaction.

c) The experimental data for a hypothetical reaction \( \text{X} + \text{Y} \rightarrow \text{Z} \) is:

Determine the rate constant and write down rate law equation from the above data. 

d) What is the order of reaction with respect to X ? 

OR

a) i) What is meant by weak electrolyte? 

ii) Derive Ostwald's dilution equation. 

iii) Point out any two limitations of Ostwald's dilution law. 

b) Predict whether precipitation will occur or not on mixing \( 20\text{ mL} \) of \( 1 \times 10^{-3}\text{ N} \) of \( \text{NaCl} \) solution with \( 80\text{ mL} \) of \( 1 \times 10^{-2}\text{N} \) \( \text{AgNO}_3 \) solution if \( \text{K}_{\text{sp}} \) for \( \text{AgCl} = 1.5 \times 10^{-10} \).\( [At.wt. of \text{Ag} = 108\text{ amu}.] \) 

What is the enthalpy change in the reaction,\( 2CO + O_2 \rightarrow 2CO_2 \) called?

A) Enthalpy of combustion                             B) Enthalpy of formation   

C)  Enthalpy of fusion                                    D) Enthalpy of reaction   

 For a reaction \( 2SO_2(g) + O_2(g) \rightarrow 2SO_3(g) \) the entropy

(A) increases (B) decreases (C) remain unchanged (D) unpredictable

Solubility product principle and common ion effect are simultaneously applied in qualitative salt analysis.

i) Distinguish between solubility product principle and common ion effect. 

ii) Apply solubility product principle and common ion effect in salt analysis of group III B metal ions. 

Or

Define heat of formation. Calculate the heat of formation of acetic acid from the following data:

\( C(s) + O_2(g) \rightarrow CO_2(g), \Delta H = -99 \ Kcal/mol \)

\( H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(l), \Delta H = -68 \ Kcal/mol \)

\( CH_3COOH(l) + 2O_2(g) \rightarrow CO_2(g) + H_2O(l), \Delta H = -208 \ Kcal/mol \)

What kind of battery is used in a laptop computer and mobile phone?

A) Li-ion battery    B) Dry cell battery     C) Fuel cell battery       D) Simple cell battery

An electrochemical cell (galvanic cell) is designed by coupling Zn-electrode with standard hydrogen electrode (SHE). Given, \( E^\circ_{Zn^{++}/Zn} = -0.76\text{ V} \) 

i) Draw the galvanic cell. 

 ii) Write down complete cell reaction.

iii) Calculate the emf of the cell. 

           OR 

  What is Hess's law of constant heat summation? Calculate the heat of formation of ethanol from the following data:

  \( H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(l), \Delta H = -286.2\text{ KJ/mol} \)

  \( C(s) + O_2(g) \rightarrow CO_2(g), \Delta H = -393.2\text{ KJ/mol} \)

\( C_2H_5OH(l) + 3O_2(g) \rightarrow 2CO_2(g) + 3H_2O(l), \Delta H = -1368\text{ KJ/mol} \)

 An electrochemical cell is constructed by using Zn electrode and Pb electrode whose standard electrode potential values are -0.76V and -0.13V respectively.

 i) Indicate anode and cathode.  

ii) Write an electro-chemical cell notation. 

 iii) Write down the redox cell reactions.

 iv) Calculate the emf of the cell.

For what purpose is the hydrogen-oxygen fuel cell used in spacecraft?
A) Power for heat and light        B) Power for pressure
C) Power for propellation           D) Power for uplift

Why is standard hydrogen electrode called reference electrode? 

 An electrochemical cell connects \( \text{E}^\circ_{\text{Zn}^{++}/\text{Zn}} \) electrode with standard hydrogen electrode and the emf of the cell is found to be \( +0.76 \text{ V} \)

i) Design cell notation indicating cathode and anode. 

 ii) Write down net cell reaction. 

 iii) What is the value of \( \text{E}^\circ_{\text{Zn}^{++}/\text{Zn}} \)? 

OR

a) State Hess's law of constant heat summation and illustrate it with an example. 

b) Heat of formation of \( \text{CO}_2 \) and \( \text{H}_2\text{O} \) are \( -94 \text{ kcal} and -68 \text{ kcal} \), respectively. Calculate heat of reaction when 2 mole of \( \text{CH}_4 \) is formed. 

Which one of the following complex ions gives tetrahedral geometry? 

A) \( [Ni(CN)_4]^{2-} \)     B) \( [NiCl_4]^{2-} \)   C) \( [PtCl_4]^{2-} \)     D) \( [CoF_6]^{3-} \)

Which of the following molecules does not act as a ligand?

A) \( CO_2 \)      B) \( NH_3 \)       C)\( H_2O \)   D) CO

A heavy metal is extracted from its oxide ore. During extraction, smelting of the calcined ore is done in a blast furnace.

a) Name the metal and the ore.

b) Draw the clean and labelled diagram of the blast furnace showing different zones.

c) Write down the balanced chemical equations of slag formation reactions.

Write two methods of preparation of corrosive sublimate. Give its action with:

a) excess of KI     b) NH₃      

\( CuSO_4 \) is not stored in aluminum bottle because

 (A) Cu-gets oxidised         (B) Cu-gets reduced

 (C) Al-gets reduced       (D) \( CuSO_4 \) gets decomposed

The iron pipes carrying drinking water are covered with Zinc to prevent from rusting this process is called...

 (A) allow formation       (B) electroplating          (C) galvanization           (D) electrifying

 Blister copper is,

 (A) ore of Cu          (B) alloy of Cu

(C) pure Cu            (D) Cu containing 1% impurity

Write down the chemistry of blue-vitriol.

A metal (M) having atomic number 30 is referred as non-typical transition metal and it belongs with the group IIB.

 i) Identify the metal (M) and write its chief ore. 

ii) Why (M) is called non-typical transition metal? 

iii) Write the chemical process occurring in reduction step during the extraction of (M)

Which of the following indicates lithophone?

A)\( \text{ZnS} + \text{BaSO}_4 \)     B) \( \text{ZnSO}_4 + \text{BaSO}_4 \)

 C) \( \text{ZnCO}_3 + \text{BaS} \)    D) \( \text{ZnS} + \text{BaSO}_3 \)

Which of the following is the purest form of iron?
A) Cast iron    B) Steel     C) Haematite    D) Wrought iron

Write the preparation, properties and uses of mercuric chloride.

A metal having electronic configuration \( [\text{Ar}] 3\text{d}^{10}, 4\text{s}^1 \) belongs with IIB of the periodic table. The metal is widely used to make electric wires and domestic cooking utensils.

a) Draw a well-labelled blast furnace for smelting the metal from its ore.

 b) Write down chemical reactions that occur in the smelting process.

The chlorinated compound 'A' reacts with acetone to give sleep-inducing drug.

a) How would you prepare compound 'A' by using one of the isomers of \( C_2H_6O \)? 

 b) What happens when compound 'A' is:

  i) Exposed in air? 

 ii) Heated with phenol in the presence of aq. \( NaOH \)? 

 Give an example of each of the following reaction.

i) Cannizzaro's reaction

ii) Aldol condensation

iii) Williamson's ether synthesis

iv) Dehydrohalogenation

v) Dehydration of alcohol. 

Which of the following mechanisms can occur in the hydrolysis of isopropyl chloride?

 A) \( \text{SN}^1 \) Mechanism                                B) \( \text{SN}^2 \) Mechanism

C) \( \text{SN}^1 \) and \( \text{SN}^2 \) Mechanism     D) Neither \( \text{SN}^1 \) nor \( \text{SN}^2 \) Mechanism

A list of organic compounds is given as follows:

Propanamine, ethoxyethane, ethyl cyanide, iodoethane and ethanol

Prepare a correct sequence of reaction chain from the above compounds using suitable reagents and conditions. 

OR

An organic compound A gives compound B when heated with silver powder. The compound B undergoes hydrolysis with water in presence of \( \text{dil. H}_2\text{SO}_4 \) and \( 1\% \text{ HgSO}_4 \) to yield C. The compound C reacts with dilute alkali to form D. The compound C can also be obtained by the reduction of ethanoyl chloride with hydrogen in presence of \( \text{Pd/BaSO}_4 \). Identify A, B, C and D with pertinent reactions.

Chlorobenzene is prepared commercially by:

(A) Dow's process      (B) Deacon's process      (C) Raschig process     (D) Etard's process

A) Identify A and B in the following reaction sequence.

i) Write down correct chemical equation to identify A and B. 

ii) What product would you obtain when A is:

a) boiled with water? 

b) treated with aniline? 

B) What happens when \( \text{C}_6\text{H}_5\text{Cl} \)is heated with chloral? 

What would be the product when ketone is treated with Grignard's reagent?

A) Primary alcohol       B) Secondary alcohol

C) Tertiary alcohol       D) Methyl alcohol 

A sequence of chemical reactions is represented as:

\( A \xrightarrow[\text{Ice cold}]{NaNO_2 + dil. HCl} B \xrightarrow{[O]}{KMnO_4 / H^+} CH_3CHO \)

a) Identify the compounds (A) and (B). 

b) Write the laboratory test of compound (B).

c) Starting from compound (B), how would you obtain nitrolic acid? 

d) Predict the product when compound (A) is heated with chloroform in alcoholic medium. 

      OR 

Make a correct sequence of reactions using suitable conditions and reagents of the following compounds.

Benzene, Benzaldehyde, Toluene, Cinnamic acid, Sodium benzoate, Benzoic acid.

An alcohol (P) having molecular formula\( C_4H_{10}O \) undergoes Victor-Meyer's test to give blue colour at the end of reaction when added KOH solution.

i) Draw structure formula and write IUPAC name of (P). 

ii) Write down complete chemical reaction for the Victor-Meyer test of (P). 

iii) How would you prepare (P), starting from \( CH_3MgBr \)? 

iv) What product would you obtain when P is oxidised? 

v) Convert propan-1-ol into propan-2-ol. 

Or

i) Give correct chemical reaction for the preparation of chlorobenzene from: 

a) benzene

b) benzene diazonium chloride

ii) Why is haloarene less reactive than haloalkane towards nucleophilic substitution reactions? 

iii) A reaction sequence is given below.

\( C_6H_5Cl \xrightarrow{(P)} C_6H_6 \xrightarrow{(Q)} C_6H_5CH_3 \xrightarrow{CrO_2 / H^+} (R) \xrightarrow{alc. KCN} (S) \)

a) Write down the reagents and conditions for (P) and (Q). 

b) Draw structural formula of (R) and (S). 

A compound 'X' undergoes reduction with \( \text{LiAlH}_4 \) to yield 'Y'. When 'Y' is passed over copper heated to \( 300^\circ\text{C} \), 'X' is formed. What is 'Y'?

A) Acetone     B) Ethanal     C) Ethanol       D) Ethoxyethane

Explain Hoffmann's method to separate ethanamine and N-methylmethanamine from their mixture. 

b) What happens when: 

i) chloroform is treated with acetone in presence of aq. \( \text{KOH} \)?

ii) ethanal reacts with 2,4–DNP ?

iii) aniline is added to ice-cold solution of sodium nitrite and hydrochloric acid?

iv) Nitro-benzene is subjected to electrolytic reduction ?

OR

a) Identify\( \text{A}, \text{B}, \text{C} and \text{D} \) in the following reaction sequence.

\( \text{A} \xrightarrow[\Delta]{\text{NaOH} + \text{CaO}} \text{B} \xrightarrow{\text{CHCl}_3 / \text{AlCl}_3} \text{C} \xrightarrow{[\text{O}]}{\text{CrO}_2\text{Cl}_2 / \text{H}^+} \text{D} \)

Compound 'C' can be obtained by Clemmensen's reduction of benzaldehyde. 

b) Explain the test of propan-1-ol and propan-2-ol by using Victor-Meyer's method in detail.

Benzoic acid gives benzene on being heated with 'X' and phenol gives benzene on being heated with 'Y'. Therefore, X and Y are respectively : 

A) Sodalime and copper          B) Zn dust and NaOH

 C) Zn dust and sodalime        D) Sodalime and Zn dust

Carbolic acid is,

 (A) phenol         (B) methanol

(C) formic acid    (D) acetic acid

Give an example of each of the following reactions.

a) Tollen's test

 b) Cannizzaro's reaction

c) Decarbonylation

d) Reimer-Tiemann's reaction

 e) Oxo-process

When the compound sodium ethoxide reacts with chloroethane, it gives the compound\( C_4H_{10}O \). What reaction is this?

A) Wurtz's reaction                B) Williamson's synthesis

C) Rosenmund's reduction     D) Dehydrohalogenation reaction

Which of the following is used to convert >C=O group to\( -CH_2- \)?

A) \( Ni / H_2 / \Delta \)        B) \( LiAlH_4 / \Delta \)     C) \( Zn-Hg / HCl / \Delta \)       D) \( Pd / H_2 / \Delta \)

Write a chemical equation for each of the following. 

 a) 2, 4-DNP test

 b) Oxo-process

c) Claisen condensation reaction

d) Wurtz-Fittig reaction

 e) Carboxylation reaction

Acetone \( \xrightarrow{NH_4OH} (X) \xrightarrow{LiAlH_4} (Y) \) in this reaction, the compound (Y) is:

(A) tertiary amine     (B) secondary amine    (C) primary amine    (D) 2 - amine propane.

8. Which of the following compound gives iodoform test?

(A) propanone      (B) propanal     (C) butanal     (D) butanol

What would be the product when benzaldehyde is heated with conc. \( \text{NaOH} \)?

A) Benzyl alcohol and sodium benzoate     B) Sodium benzoate and benzaldehyde

C) Sodium benzoate and benzene             D) Benzyl alcohol and benzene

a) Give any two chemical reactions for the preparation of ethanoic acid. 

b) How does ethanoic acid react with 

i) \( P_2O_5 \)

ii)\( NH_3 \)?

c) A carbonyl compound 'A' gives both Tollen's and iodoform tests positively.

i) Identify the compound 'A'. 

ii) How does the compound 'A' react with dil. NaOH? Give chemical equation involved. 

iii) Write the chemical equation when compound 'A' reacts with HCN followed by hydrolysis. 

a) An aromatic compound (A) undergoes Sandmeyer's reaction to give (B). The compound (B) is reduced with Ni-Al in presence of alkali to give compound (C). The compound (C) further reacts with \( CH_3Cl \) in the presence of Anhydrous \( AlCl_3 \). The compound (B) when heated with chloral in acidic medium gives a common insecticide. Identify (A), (B), (C) and (D) giving complete reaction. 

 b) How do you separate the isomers of\( C_3H_9N \) by Hoffmann's method? Explain with suitable chemical equations.

An organic compound (M) \( C_4H_8O_2 \) undergoes acid hydrolysis to give a carboxylic acid (N) and an alcohol (P). The alcohol (P) is oxidised with \( KMNO_4/H^+ \) to give the carboxylic acid (N)

i) Draw the structural formula of (M), (N) and (P).

ii) What product will you obtain when (M) is reduced in \( LiAlH_4 \)? 

OR

Vinegar is an aqueous solution of acetic acid containing about 5 to 8% by volume in the aqueous solution.

i) Give any three methods of preparation of acetic acid. 

ii) Convert acetic acid into acetic anhydride. 

iii) Mention an important use of vinegar. 

Starting from \( \text{CH}_3\text{MgBr} \), how you would prepare ethanoic acid? Write the action of ethanoic acid on: 

 i) \( \text{NH}_3 \)                ii) \( \text{SOCl}_2 \)              iii) \( \text{P}_2\text{O}_5 \)               iv)\( \text{LiAlH}_4 \)

i) Starting from nitrobenzene, how would you prepare aniline? Convert aniline into: 

a) phenyl isocyanide

b) azo-dye

 ii) Nitrobenzene prefers electrophilic substitution reaction at meta-position. Explain.

Nitrobenzene can be prepared from benzene by using a mixture of conc. nitric acid and conc.\( \text{H}_2\text{SO}_4 \) in the nitrating mixture. What is the role of nitric acid?

 A) A base     B) An acid     C) A catalyst     D) A reducing agent

\( CH_3Cl \xrightarrow{Alc. AgCN}  (A) \xrightarrow[\Delta]{LiAlH_4} (B) \) what would be the product B?

 A) Methanamine     B) Ethanamine     C) N-methyl methanamine      D) N-methyl ethanamine

 The colourless liquid (A) reacts with sodium metal at room temperature to produce sodium salt of carboxylic acid and ammonia. Identify liquid compound (A)

 (A) propanamide         (B) propanoic acid

(C) formamide              (D) methyl ethanoate.

You are given a bottle containing a mixture of primary, secondary and tertiary amine. Apply Hoffmann's method to separate each amine in its pure state. 

You are given (I) aniline (II) o-nitro aniline (III) p-nitro aniline and (IV) m-nitroaniline. What is the order of increasing basic nature?

A) \( \text{II} < \text{I} < \text{III} < \text{IV} \)    B) \( \text{I} < \text{II} < \text{III} < \text{IV} \)

C)\( \text{II} < \text{III} < \text{I} < \text{IV} \)     D) \( \text{II} < \text{III} < \text{IV} < \text{I} \)

Represent a regular sequence of chemical reaction of the following sets of organic compounds using suitable reagents, catalysts or conditions with proper reasons. \( CH_3COOH, \) \( CH_3Br \), \( CH_3COOMgBr, \)    \( CH_3MgBr \)

a) Define homopolymer and co-polymer.

 b) Differentiate between paper and pulp. 

 c) Distinguish between OPC and PPC cement. 

 d) Write down any two uses of radioisotopes in medical field. 

 Write short note of pulp and paper industry in Nepal.

b) Give structural formula of monomers and one use of each polymer. 

 i) Polyethene ii) Teflon iii) Bakelite iv) Polystyrene

a) Explain the quality control system in the manufacture of portland cement. 

b) Give the correct structure of the following compounds

. i) Aspirin ii) DDT

c) Write any two differences between paper and pulp. 

d) What is meant by artificial radioactivity ? Write an example of it.