SAMPLE QUESTION PAPER (2021-22)
CHEMISTRY (043)
TERM II
CLASS 12
Time: 2 Hrs Max. Marks: 35
GENERAL INSTRUCTIONS
1. There are 12 questions in this question paper with internal choice.
2. SECTION – A, Q. No. 1 – 3 are very short answer questions carrying 2 Marks each.
3. SECTION – B, Q. No. 4 – 11 are short answer questions carrying 3 Marks each.
4. SECTION – C, Q. No. 12 is case based question carrying 5 Marks.
5. All questions are compulsory.
6. Use of log tables and Calculator is not allowed.
SECTION A
Attempt all questions: –
Q1. For the reaction:
(i) What is the order and molecularity of the reaction?
(ii) Write unit of k.
Q2. Give reasons:
(i) The -hydrogen atoms of aldehydes and ketones are acidic in nature.
(ii) Propanone is less reactive than Ethanal towards Nucleophilic addition reactions.
Q3. Draw structures of the following derivatives:
(i) Cyanohydrin of cyclobutanone
(ii) Hemiacetal of ethanol
SECTION B
Q4. A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when
75% of the reaction will be completed. [Given log2 = 0.3010, log3 = 0.4771, log4 = 0.6021]
OR
The decomposition of N2O5 (g) is a first order reaction with rate constant of 5 x 10-4 s-1 at 450 C
2N2O5 (g) → 4NO2 (g) + O2 (g)
If the initial concentration of N2O5 is 0.25 M. calculate its initial concentration after 2 minutes.
Also calculate the half-life for decomposition of N2O5 (g).
Q5. (a) Adsorption of gas on the surface of solid is generally accompanied by decrease in
entropy. Still it is a spontaneous process. Explain.
(b) How does an increase in temperature affect both physical as well as chemical adsorption?
(c) Identify the functional groups in the molecular of non-ionic detergent.
Q6. Write the difference in each of the following:
(i) Multimolecular colloids and Associated colloids
(ii) Coagulation and Peptisation
(iii) Lyophilic sol and lyophobic sol.
Q7. The magnetic moments of few transition metal ions are given below:
Which of the given metal ions?
(i) Has maximum number of unpaired electrons?
(ii) Forms colourless aqueous solution?
(iii) Exhibits the most stable +3 oxidation state?
OR
Account for the following:
(i) CuCl2 is more stable than Cu2Cl2.
(ii) Transition metals form complex compounds.
(iii) Atomic radii of 4d and 5d series elements are nearly same.
Q8. (a) What type of isomerism is shown by the complex [Co (NH3)5 (SCN)]2+?
(b) Why is [NiCl4]2- paramagnetic while [Ni (CN)4]2- is diamagnetic?
(c) Why are low spin tetrahedral complexes rarely observed?
OR
(a) What type of isomerism is shown by the complex [Cr(H2O)6]Cl3?
(b) On the basis of crystal field theory, write the electronic configuration for d4ion if ∆0 >P.
(c) Write the hybridization and shape of [CoF6]3- . (Atomic number of Co = 27)
Q9. Give reasons:
(i) Benzoic acid does not give Friedel-Craft reaction.
(ii) O2N-CH2-COOH has lower pKa value than CH3COOH.
(iii) (CH3)2CH-CHO undergoes Aldol condensation whereas (CH3)3C-CHO does not.
Q10. (a) Write the structure of main products when aniline reacts with the following reagents:
(i) HCl
(ii) Bromine water
(iii) (CH3CO)2O/pyridine
Q11. (a) Arrange the following in the increasing order of their basic character in an aqueous
solution: C2H5NH2, (C2H5)2NH, (C2H5)3N
(b) Arrange the following in the increasing order of their boiling points:
C2H5NH2, C2H5OH, (CH3)3N
(c) Give a simple chemical test to distinguish between the following pair of compounds:
(CH3)2NH, and (CH3)3N
SECTION C
Q12. Case Based Question:
Read the passage given below and answer the following questions:
Weak electrolyte like acetic acid has lower degree of dissociation at higher concentration and hence for such electrolytes, the change in Ʌm with dilution is due to increase the degree of dissociation and consequently the number of ions in total volume of solution that contains one mol of electrolyte. In such cases Ʌm increases steeply on dilution, especially near lower concentrations. Therefore, Ʌ0m cannot be obtained by extrapolation of Ʌm to zero concentration. At infinite dilution (i.e. concentration c –> zero) electrolyte dissociates completely (α = 1), but at such low concentration the conductivity of the solution is so low that it cannot be measures accurately. Therefore, Ʌ0m for weak electrolytes is obtained by using Kohlrausch’s law of independent migration of ions.
(i) Which of the following is not a weak electrolyte?
(a) Ammonium acetate
(b) Acetic acid
(c) Ammonium chloride
(d) Ammonium hydroxide
(ii) The value of Ʌm in case of a weak electrolyte on dilution.
(a) Increases steeply
(b) Decreases steeply
(c) Increases gradually
(d) Decreases gradually
(iii) Ʌ0m for weak electrolytes is obtained by using
(a) Kohlrausch’s law
(b) Arrhenius law
(c) Avogadro’s law
(d) Maxwell’s law
(iv) For strong electrolytes, Ʌm increases slowly with dilution and can be represented by the equation:
(a) Ʌ0m = Ʌm – AC1/2
(b) Ʌm = Ʌ0m – AC1/2
(c) Ʌ0m = Ʌm – AC
(d) Ʌm = Ʌ0m – AC
(v) Limiting molar conductivity (S cm mol-1) of K+ and SO42-are respectively 73.5 and 160.0. The Limiting molar conductivity of K2SO4 will be
(a) 393.5
(b) 233.5
(c) 467
(d) 307