SET-1

EXAM DATE: 12/03/2019

Code No. 56/1/1

Class XII CHEMISTRY (Theory) (CBSE 2019)

Time: 3 Hrs.

Max. Marks: 70

GENERAL INSTRUCTIONS:

1. All questions are compulsory.
2. Section A: Q. no. 1 to 5 are very short-answer questions and carry 1 mark each.
3. Section B : Q. no. 6 to 12 are short-answer questions and carry 2 marks each.
4. Section C: Q. no. 13 to 24 are also short-answer questions and carry 3 marks each.
5. Section D: Q. no. 25 to 27 are long-answer questions and carry 5 marks each.

1. There is no overall choice. However, an internal choice has been provided in two questions of one mark, two questions of two marks, four questions of three marks and all the three questions of five marks weightage. You have to attempt only one of the choices in such questions.

1. Use log tables if necessary. Use of calculators is not allowed.

Section-A

1. Out of NaCl and AgCl, which one shows Frenkel defect and why? [1]
2. Arrange the following in increasing order of boiling points: [1]

<math>(CH_3)_3N</math>, <math>C_2H_5OH</math>, <math>C_2H_5NH_2</math>

1. Why are medicines more effective in colloidal state? [1]

OR

What is difference between an emulsion and a gel?

1. Define ambidient nucleophile with an example. [1]
2. What is the basic structural difference between glucose and fructose? [1]

OR Write the products obtained after hydrolysis of lactose.

Section-B

1. Write balanced chemical equations for the following processes:

$[2]$

1. XeF₂ undergoes hydrolysis.
2. MnO₂ is heated with conc. HCl.

OR

Arrange the following in order of property indicated for each set:

1. <math>H_2O</math>, <math>H_2S</math>, <math>H_2Se</math>, <math>H_2Te</math> – increasing acidic character
2. HF, HCl, HBr, HI decreasing bond enthalpy

7. State Raoult's law for a solution containing volatile components. Write two characteristics of the solution which obeys Raoult's law at all concentrations. [2]

1. For a reaction

[2] <math>2H_2O_2 \xrightarrow{\Gamma} 2H_2O + O_2</math>

the proposed mechanism is as given below:

1. <math>H_2O_2 + I^- \rightarrow H_2O + IO^-</math> (slow)
2. <math>H_2O_2 + IO^- \rightarrow H_2O + I^- + O_2</math> (fast)
3. Write rate law for the reaction.
4. Write the overall order of reaction.
5. Out of steps (1) and (2), which one is rate determining step?

1. When MnO₂ is fused with KOH in the presence of KNO₃ as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in acidic solution to give purple compound (B). An alkaline solution of compound (B) oxidises KI to compound (C) whereas an acidified solution of

compound (B) oxidises KI to (D). Identify (A), (B), (C), and (D). [2]

1. Write IUPAC name of the complex [Pt(en)₂Cl₂]. Draw structures of geometrical isomers for this

complex. [2]

OR

Using IUPAC norms write the formulae for the following:

1. Hexaamminecobalt(III) sulphate
2. Potassium trioxalatochromate(III)
3. Out of <math>[CoF_6]^{3-}</math> and <math>[Co(en)_3]^{3+}</math>, which one complex is
4. paramagnetic
5. more stable

$[2]$

1. inner orbital complex and
2. high spin complex

(Atomic no. of <math>Co = 27</math>)