CBSE Question Papers 2005 - Chemistry

by Deepa Mittal

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Chemistry

Time allowed : 3 hours

Maximum Marks : 70

General Instructions :

All questions are compulsory.
Marks for each question are indicated against it.
Question numbers 1 to 5 are very short-answer, carrying 1 mark each. Answer these in one word or about one-sentence each.
Question numbers 6 to 12 are short-answer, carrying 2 marks each. Answer these in about 30 words each.
Question numbers 13 to 24 are short-answer questions of 3 marks each. Answer these in about 40 words each.
Question numbers 25 and 27 are long-answer questions of 5 marks each. Answer these in about 70 words each.
Use Log Tables, if necessary. Use of calculators is not permitted.

QUESTION PAPER CODE 56/1/1

What is the maximum possible corrdination number of an atom in an hcp crystal structure of an element ?
State the formula relating pressure of a gas with its mole fraction in a liquid solution in contact with it.
Express the relation between the half-life period of a reactant and its initial concentration if the reaction involved is of second order.
How are formalin and trioxane related to methanal?
Why are primary amines higher boiling than tertiary amines?
Show that the Heisenberg Uncertainty Principle is of negligible significance for an object of $10^{-6}kg$ mass. $(\frac {h}{4\pi}=0.528*10^{-34} kg$ $m^2s^{-1})$

or
<br.On the basis of Heisenberg Uncertainty Principle show that electron $(mass=9.10^{-31}kg)$ cannot exist within an atomic nucleus of radius $10^{-15}m.$ $(\frac {h}{4\pi}=0.528*10^{-34} kg$ $m^2s^{-1})$
On the basis of the following $\Delta G_r^\circ$ values at 1073 K :

$S_2(s)+2O_2(g)\rightarrow 2SO(2g);$ $\Delta G^\circ =-544 kJ mol^{-1}$

$2Zn(s)+O_2(g)\rightarrow 2ZnO(s);$ $\Delta G_r^\circ =-480 kJ mol^{-1}$

$2Zn(s)+S_2(s)\rightarrow 2ZnS(s);$ $\Delta G_r^\circ =-293 kJ mol ^{-1}$

Show that the roasing of zinc sulphide to form zinc oxide is a spontaneous process.
Write one chemical reaction each to show that
1. Tin (II) chloride is a reducing agent.
2. Chlorine gas can be obtained from bleaching powder.
Describe the steps involved in the preparation of either potassium dichromate from sodium chromate or potassium permanganate from manganese dioxide.
What are enantiomers and diastereomers ? Differentiate between chiral and achiral molecules.