Subject: Chemistry
Class XII
Time Allowed: 3 hours
Max. Marks: 70
General Instructions:
1. Section A consists of Q.1 to Q. 21 are of one mark each
2. Section B consists of Q. 22 to 24 are of 1 mark and Q. 25 to Q. 30 are of 2 marks each
3. Section C consists of Q.31 to Q.38 are of 3 marks each
4. Section D consists of Q.39 to Q. 40 are of 5 marks each
5. Use of log table is not allowed
6. Attempt all questions
Section-A
1) A molal solution is one which contains 1 mole of solute in
a. 1L of solution b. 1L of solvent c. 1kg of solvent d. 1kg of solution
2) The volume of 80% sulphuric acid by weight( density = 1.80 g / ml )required to prepare 1 L of 0.2 M sulphuric acid is
a. 14.7 b. 29.4 c. 6.8 d. 13.60
3) At 250C the molar conductance at infinite dilution for strong electrolyte NaOH, NaCl and BaCl2 are 248×10-4, 126×10-4 and 280×10-4 Sm2 mol-1 respectively. The molar conductance of Ba(OH)2 in Sm2 mol-1 is
a. 408×10-4 b. 284×10-4 c. 524×10-4 d. 586×10-4
4) Consider a reaction 2x + 3y >>>>Z. If the rate of disappearance of X is 0.072 mole per litre per second, then the rate of appearance of Z is
a. 0.072 mol L-1S-1 b. 0.142 mol L-1S-1 c. 0.036 mol L-1S-1 d. 0.024 mol L-1S-1
5) The reagents used for the conversion of aniline to chlorobenzene are
a. CuCl2/HCl b. Cu2Cl2/HCl
c. NaNO2, Cu2Cl2/HCl(0-5°C) d. Cu/HCl
6) SN1 reaction of alkyl halides leads to
a. Retention of configuration
b. Racemization
c. Inversion of configuration
d. None of these
7) Benzyl ethyl Ether on reaction with HI at 373 K gives
a. Benzyl iodide, ethanol
b. Benzene, ethyl iodide
c. Benzyl alcohol, ethyl iodide
d. Benzyl alcohol, methyl iodide
8) Which of the following statement is incorrect
- Both ethanol and phenol react with sodium metal and evolve hydrogen gas
- Alcohols are stronger acid than Water
- Ortho nitrophenol has lower pka value then meta nitrophenol
- Para cresol is less acidic than phenol.
9) The geometry and magnetic behaviour of the complex [Ni(CO)4] are
a. Square planar geometry and diamagnetic
b. Tetrahedral geometry and diamagnetic
c. Square planar geometry and paramagnetic
d. tetrahedral geometry and paramagnetic
10) How many ions are produced from the complex [Co(NH3)5Cl] Cl2 in solution
a. 4 b. 2 c. 3 d. 5
Case study: Read the given passage and answer the question that follows:
When phenol is refluxed with chloroform in the presence of aqueous Sodium Hydroxide or potassium Hydroxide followed by hydrolysis, an aldehyde group is introduced in the benzene ring at a position ortho to the phenolic group. The product is called ortho hydroxy benzaldehyde. In addition to Ortho product a small amount of para product is also formed but the major product is ortho. But if one of the position is occupied then para product is formed. The reaction is electrophilic substitution reaction.
11) What is the name of reaction?
12) Write the major product formed if CCl4 is used in place of CHCl3.
13) Write the reaction of product of reaction with acetic anhydride in presence of conc. H2SO4.
14) What is the electrophile in the reaction?
15) What happens when phenol undergo catalytic reduction?
In the following question are statement of assertion followed by a statement of reason is given choose the correct answer out of the following choices:
- assertion and reason both are correct statements and reason is a correct explanation for assertion
- Assertion and reason both are correct statements but reason is not the correct explanation for assertion
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
16) Assertion: osmotic pressure is a colligative property.
Reason: osmotic pressure of a solution depends on molar concentration of solute at any temperature T.
17) Assertion: copper sulphate solution can be kept in a zinc vessel.
Reason: The position of zinc is higher than copper in electrochemical series.
18) Assertion: For Complex reaction order and molecularity are not same.
Reason: Order of reaction can never be zero.
19) Assertion: The ligands NO2– & ONO– are ambident ligands.
Reason: They are Bidentate ligands.
20) Assertion: tertiary butyl bromide undergo SN1 nucleophilic substitution reaction readily then n-butyl bromide
Reason: It proceed by the formation of stable carbo cation.
21) Assertion: 2-Bromobutane on reaction with alcoholic KOH gives 1-Butene as the major product.
Reason: But-1-ene is less stable than but -2-ene.
Section – B
22) State Raoults law for a solution containing volatile component. What is the similarity between Raoults law and Henry’s law?
23) What is the difference between an ambident ligand and chelating ligand.?
24) State kohlrausch’s law of independent Migration of ions.
25) The resistance of a conductivity cell containing 0.001M KCl solution at 298 k is 1500 ohm. What is the cell constant if the conductivity of 0.001 M KCl solution at 298 k is 0.146×10–3 Scm-1.
26) Write two differences between order of reaction and molecularity of reaction.
27) A reaction is first order in X and second order in Y.
- How is the rate affected on increasing the concentration of Y three times.
- How is the rate affected when the concentration of both X and Y are doubled?
28) Convert the following
- But -1-ene to 1- iodo butane
- Benzene to acetophenone
29) Alcohols are easily protonated in comparison to phenol. Explain
30) Explain the mechanism of the following reaction.
Section – C
31) a. Define an ideal solution and write its 2 characteristics.
b. 18 g of glucose (molar mass 180 gram per mole) is dissolved in 1 kg of water in a sauce pan. At what temperature will this solution boil?
(Kb for water=0.52 K kg/mol, B.P of pure water= 373.15 K)
32) Identify A, B, C, D, E and F in the following.
33) Give the final products expected from the following reactions.
- Hydroboration of propene followed by oxidation with H2O2 in alkaline medium.
- Dehydration of (CH3)3-OH by heating it with 20% H3PO4 at 358 K
- C6H5CH2OC6H5 with HI.
34) a. What type of a battery is a Lead Storage battery? Write the anode and the cathode reaction and the overall reaction occurring in a Lead Storage battery when current is drawn from it.
b. Write the cell reaction and calculate the emf of the following cell at 298 K
Sn(s)l Sn2+(0.004) ll H+(0.020M) l H2(g) (1bar) l Pt(s)
Given: E° Sn2+/Sn= -0.14V
(Log4=.6021, Log2=.3010)
35) The decomposition of a hydrocarbon has value of rate constant as 2.5×104 s-1 at 27°C .At what temperature would rate constant be 7.5×104 s-1 if energy of activation is
19.147×103 J /mol.
(Log3=.4771, log 5=.6990)
36) a. Difference between double salt and coordination complex
b. Write the IUPAC name and hybridization of [CoF6]3-.
37) Name the following coordination entities and describe their structure and magnetic character.
- [Fe(CN)6]4-
- [Cr (NH3)4Cl2]+
- [Ni(CN)4]2-
38) Show that time required for 99% completion is twice the time required for the completion of 90%reaction.
Section – D
39) a. Account for the following:
1. Ortho nitrophenol is more steam volatile than para nitrophenol
2. Tert butyl chloride on heating with sodium methoxide gives 2 – methyl propene instead of tert- butyl methylether.
b. Write the reaction involved in following
1.Kolbes reaction
2.Friedel craft Alkylation of phenol
c. Give simple test to distinguish ethanol and phenol
40) a. Out of the following pairs, predict with reason which pair will allow greater conduction of electricity:
(i) Silver wire at 300C or silver wire at 500C.
(ii) 0.1 M CH3COOH solution or 1 M CH3COOH solution.
(iii) KCl solution at 200C or KCl solution at 500C
b. Give two points of difference between electrochemical and electrolytic cells.