Class 12 Chemistry

To estimate the chloride ion present in tap water, volumetric analysis has been commonly used in laboratory. Which of the following solutions can be used for the above mentioned titration ?

A)\( \text{BaCl}_2 \)     B)\( \text{NaOH} \)    C) \( \text{K}_2\text{Cr}_2\text{O}_7 \)        D) \( \text{AgNO}_3 \)

The half-life of a certain reaction is 50 seconds and it remains constant even if the initial concentration of the reactant is doubled. What is the order of the reaction ?

A) Zero order reaction

B) First order reaction

C) Second order reaction

D) Pseudo-first order reaction

Gibbs-Helmholtz equation is represented as : \( \Delta G = \Delta H - T\Delta S \)

For what value of\( \Delta G \)will the reaction be spontaneous ?

A) Positive    B) Zero   C) Negative       D) Infinite

Standard reduction potential values for P, Q, R and S are +0.34V, -0.76V, +0.0V and -3.05V, respectively. What is the correct order of their reducing power ?

A) P > R > Q > S                                     B) S > R > Q > P

C) Q > P > S > R                                     D) S > Q > R > P

A deep blue complex is formed when conc. ammonium hydroxide is added to an aqueous solution of \( \text{CuSO}_4 \). Which of the following formulae represents the complex ?

A) \( [\text{Cu}(\text{NH}_3)_4]^{2+} \)                                                           B) \( [\text{Cu}(\text{NH}_3)_4]^+ \)

C) \( [\text{Cu}(\text{NH}_3)_2]^{2+} \)                                                           D) \( [\text{Cu}(\text{NH}_3)_6]^{2+} \)

Which of the following is the maximum possible oxidation state of the transition metals in 3d series ?

A) +3               B) +6              C) +7                     D) +8

Which of the following are organometallic compounds ?

i) \( \text{CH}_3\text{MgI} \)                                 ii) \( \text{Ni}(\text{CO})_4 \)

iii) \( \text{C}_2\text{H}_5\text{Li} \)                                 iv)\( \text{C}_2\text{H}_5\text{ONa} \)

v) \( (\text{C}_2\text{H}_5)_2\text{SnCl}_2 \)

A) i) and ii) only                            B) i), ii) and iii) only

C) i), ii), iii) and iv) only                D) i), ii), iii) and v) only

The organic compound (X) boiled with water gives phenol. What is the compound (X) ?

A) Chlorobenzene                               B) Benzenediazonium chloride

C) Benzenesulphonic                           D) Aniline

Which of the following compounds gives positive carbylamine reaction ?

A)\( (\text{CH}_3)_2\text{NH} \)                         B) \( (\text{CH}_3)_3\text{N} \)

C) \( (\text{CH}_3)_4\text{N}^+ \)                          D) \( \text{CH}_3\text{NH}_2 \)

A compound 'Z' with molecular formula\( \text{C}_3\text{H}_4\text{O}_4 \) is heated to produce compound 'Y' and \( \text{CO}_2 \) gas. Heating of compound 'Y' with \( \text{P}_2\text{O}_5 \) forms compound 'X' and water molecule. Identify the compound 'X'.

 A) Ethanoic acid            B) Ethanoic anhydirde            C) Methanoic anhydride                      D) Ethanal

A sequence of reactions is represented as :

\( \text{Benzene} \xrightarrow[\text{Anhy. AlCl}_3]{\text{CH}_3\text{Cl}} (A) \xrightarrow{[\text{O}]}{\text{CrO}_3} (B) \xrightarrow[\text{Reflux}]{\text{alc. KCN}} (C) \)

Predict the name of reaction that converts (B) to (C).

A) Benzoin condensation     B) Perkin's condensation        C) Aldol condensation       D) Claisen condensation

Define instantaneous rate of reaction. Write down the rate expressions of the following reaction.

If \( 2.24\text{ litres} \) of \( \text{O}_2 \) at NTP is produced in \( 30\text{ minutes} \), what is the rate of disappearance of \( \text{N}_2\text{O}_5(g) \) ?

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

Or

You are given the standard reduction potentials,

Answer the following questions :

a) What is standard electrode potential ? 

b) Construct the galvanic cell notation for the given electrodes indicating anode and cathode. 

c) Write the complete cell reaction for the given cell. 

d) Calculate the cell potential for the given cell at \( 25^\circ\text{C} \). 

A chemical reaction occurs as follows :

a) Identify the compound 'B' in the above reaction. 

b) Which substitution reaction mechanism occurs in the above reaction and why ? 

c) What is the product formed when alc. KOH solution is used instead of aq. KOH in the above reaction ? 

d) How can you obtain nitropropane from compound 'A' ? 

A list of compounds is given as follows :

P-aminoazobenzene, Benzenediazonium chloride, Aniline, Nitrobenzene, Phenol and Benzene

From the above list of compounds, prepare a sequence of reaction chain with suitable conditions and reagents.

An aliphatic compound (A) reacts with \( \text{SOCl}_2 \) to give (B). The compound (B) is heated with ammonia to produce (C). The compound (C) is further heated with \( \text{Br}_2/\text{KOH} \) to yield (D). The compound (D) gives (E) when treated with \( \text{NaNO}_2/\text{HCl} \)at low temperature. The compound (E) is a primary alcohol which gives positive iodoform test. Identify compound (A) to (E) with the reactions involved. 

Write the chemical equations to illustrate the following reactions : 

a) 2,4-DNP test

b) Reimer-Tiemann reaction

c) Williamson's reaction

d) Perkin's condensation reaction

e) Wurtz-Fittig's reaction

You are given the mixture of two compounds A and B.

How would you separate their mixture by applying Hoffmann's method ? Give the nitrous acid test to distinguish between compounds A and B.

The metal 'M' with electronic configuration \( [\text{Ar}]\,3d^{10}4s^2 \) belongs to group IIB in the periodic table and is commonly called 'Jasta'.

a) Identify metal 'M' and write its main ore. 

b) Why is metal 'M' not considered as transition element ? 

c) Draw the vertical retort. Write its reduction reaction. 

d) What happens when metal 'M' is exposed to air for a long time ? 

What is rusting ? Describe the electrochemical theory of rusting of iron. List any two methods for the prevention of rusting.

Deduce the normality equation, \( N_1V_1 = N_2V_2 \). Experimental data obtained by titrating decinormal solution of oxalic acid with potassium permanganate solution are given below.

a) Name the above titration. 

b) Calculate the equivalent weight of\( \text{KMnO}_4 \) 

c) Calculate the normality of \( \text{KMnO}_4 \) from the above data. 

d) Why is \( \text{dil. H}_2\text{SO}_4 \) added to the conical flask containing standard oxalic acid before titrating with \( \text{KMnO}_4 \) solution ? 

e) Identify the titrant and titrand in this titration. 

a) Write the applications of solubility product principle and common ion effect in qualitative salt analysis. 

b) Differentiate between Bronsted-Lowry and Lewis concept of bases. 

c) Calculate the degree of ionization of $\text{HCN}$ having concentration \( 0.01\text{M} (K_a \text{ of HCN} = 4.8 \times 10^{-10}) \). Also calculate\( \text{H}^+ \) concentration and \( \text{pH} \) of the solution. 

An organic compound (X) reacts with Grignard's reagent to give (Y), which on oxidation gives (Z). All of the compounds (X), (Y) and (Z) give positive iodoform test.

a) Identify the compounds (X), (Y) and (Z) with reactions and conditions involved. 

b) Why do these compounds give positive iodoform test ?

c) How would you convert compound (Y) into pseudonitrol ? 

d) Write any two methods for the preparation of compound (Z). 

Or

How will you carry out the following conversions ?

a) Ethanol into chloroform 

b) Phenol into DDT 

c) Ethoxyethane into methoxymethane 

d) Aniline into chlorobenzene 

Answer the following questions :

a) What are the raw materials for the production of paper ? 

b) Draw the flowsheet diagram for the manufacture of Portland cement. 

c) Nuclear fusion reaction is also called thermonuclear reaction. Why ? 

d) How are addition and condensation polymers formed ? Write an example of each.