Chemistry - 1997( I.C.S.E)
You are on questions 2 to 7 of Set I

SCIENCE
SECTION - II (40 Marks )
Answer any four questions

Q 2(a) (i) Name the oxide of sulphur which react with water to give sulphuric acid.
(ii) In the contact Process the direct reaction between the oxide of sulphur and water is avoided. In the process, what dfoes the oxide of sulphur react with instead of water and what is the name of the product?
(iii) Give the name and formula of the acid salt which can give sodium ions and sulphate ions in solution.

Q 2(b) The metal zinc is extracted from the ore zinc blende.
(i) Name the zinc compound in zinc blende.
(ii) Zinc blend when rosted in air gives off a gas which, iff allowed to escape, would constitute an atmospheric pollutant. What is this gas?
(iii) What particular polluting effect does this gas have?

Q 2 (c) Write correctly balanced equations for the   reaction in dilute sulphuric acid with each of the following :
(i) Copper carbonate (ii) Lead nitrate solution (iii) Zinc hydroxide

Q 3 (b) Industrically ammonia is obtained by direct combination between nitrogen and hydrogen.
(i) Write the correctly balance equation for the direct combination of nitrogen and hydrogen?
(ii) Which of the metals - iron, platinum. copper catalyse - this direct combination?
(iii) Is the formation of ammonia promoted by the use of high pressure or low pressure?


Q 3 (c) (i) Is ammonia more dense or less dense than air?
(ii) What property of ammonia is demonstrated by the Fountain Experiment?
(iii) Write the correctly balanced equation for the reaction between ammonia and sulpuric acid.

Q 4 (b) Ammonia burn in oxygen and the combustion, in the presence of a catalyst,may be represented by :
2NH₃ + 2_1/2O₂ ® 2NO + 3H₂O
(i) What mass of steam is prodused when 1.5g of nitrogen monooxide is formed?
(ii) What volume of oxygen, at stp, is required to form 10 moles of products? [H = 1: N = 14 : O = 16. 1mole of gas occupies 22.4dm³ (22.4 liter) at stp].

Q 5 (b) (i) Metals are generally  solid at room tempreature. Name the metal which is liquid at room tempreature (say 25^oC)
(ii) Which allotrope of the non - metal carbon conducts electricity?

Q 5 (c) (i) How many valence electrons are present in :
(1) Metals
(2) Non - Metals?

(ii) Name all the particles found in a solution of sodium chloride?

Q 6 (a) (i) Ethane and chlorine react together to form monochloroethane(ethyl chloride).
(1) Write down the structural formula of ethane.
(2) What type of reaction has taken place between ethane and chlorine.

Q 6 (a)(ii) The type of reaction between ethene and chlorine is different from that between ethane and chlorine.
(1) What is the type of reaction between ethene and chlorine?
(2) What fercture of the ethene structure makes such a reaction possible ?
(3) Name the product of the reaction between ethene and chlorine.

Q 6 (b) Ethane burns completely in air or oxygen to give carbon dioxide(and water vapour). With a limited supply of air/oxygen carbon monoxide is formed. The same gases are found in automobile exhaust gases. Both gases can be considered as atmospheric pollutants.
(i) Write the equation of the complete combustion of ethane.
(ii) What danger is associated with carbon monoxide.
(iii) What effect is associated with too much carbon dioxide in the atmosphere
(iv) Burning acetylene (ethyne) in oxygen under appropriate condition produces a very hot flame. What is this hot flame used for?

Q 7(a) Solution P has a pH of 13,solution Q has a pH of 6 and solution R has a pH of 2.
(i) Which solution will liberate ammonia from ammonium sulphate on heating?
(ii) Which solution is a strong acid?
(iii) Which solution contains solute molecules as well as ions?

Q 7(b) From the list of substances given below ,choose the pair required to prepare the salts (i) to (iii) in the laboratory and write down the relevant equations .

The substance are :
chlorine , iron, lead, lead nitrate solution, sodium nitrate solution, iron (III) carbonate, lead carbonate, iron (III) hydroxide, sodium hydroxide solution and dilute hydrochloric acid.

The salts are :
(i) sodium chloride.
(ii) lead chloride.
(iii) anhydrous iron (III) chloride.

Q 7(c) All ammonium salts are decomposed on heating. What other property do ammonium salts have in common?

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