Chemistry - 1997 ( I.C.S.E)
You are on question 1 of Set I

-Answer to this paper must be written on the paper provided separately .
-You will NOT be allowed to write during the first 15 muintes .
-This time is to be spent in reading the question paper.
-The time given at the head this paper is the time allowed for writing the answer.

- This question paper is divided into two section. Section I contains One question with eight   parts (a) to (h):    all eight parts are to be answered. Section II contains six questions,   numbered 2 to 7.
- You are to answer four of these questions.

The intented marks for questions or parts of questions are given in brackets [ ]. All working, including rough work, Should be done on the same sheet as the rest of the answer 5.

SCIENCE
SECTION - I (40 - Marks)
Answer all questions.

Q 1. (a) Answer the questions below, relating your answers only to salts in the following list :
Sodium Chloride, anhydrous calcium chloride, copper sulphate - 5- water.
(i) What name is given to the water in the compound copper sulphate - 5-water?

(ii) If copper sulphate -5 - water is heated, the water is driven off leaving anhydrous copper sulphate.

(A) What is the colour of anhydrous sulphate?

(B) By what means, other than heating, could you dehydrate copper sulphate -5-water and obtain anhydrous copper sulphate?

(iii) What is deliquescence ?

(iv) Which one of  the salts in the given list is deliquescent ?

Q 1(b) State what you see when :
(i)  a piece of moist blue litmus paper is placed in a gas jar of chlorine.
(ii) a piece of moist red litmus paper is placed in a gas jar of ammonia .
(iii)Silver nitrate solution is added to dilute hydrochloric acid.
(iv)Zinc oxide is heated.
(v) A glowing splint is introduced into a gas jar containing oxygen.

Q 1 (c) Write correctly balanced equations for the following reactions :
(i) Molten sodium and chlorine.
(ii) Nitrogen and oxygen when lightning strikes.
(iii) Iron and dilute sulphuric acid.
(iv) Decomposition of hypochlorous acid in sunlight.
(v) Action of heat on potassium nitrate.


Q 1(d) Water can be split into hydrogen and oxygen under suitable conditions.
The equation representing the change is :
2H₂O(l)        ---------------> 2H₂(g) + O₂(g).
(i) If  a given experiment result in 2500 cm³ of hydrogen being produced, what value of oxygen is liberated at the same time under the same conditions of temperature and pressure?

(ii) The 2500 cm³ of hydrogen is subjected to 2 _1/2   times increases in pressure (temperature remaining constant ). What volume will the hydrogen now occupy ?

(iii) Taking the volume of hydrogen calculated in (d) (ii), what change must be made in the kelvin (absolute) temprature to return the volume to  2500 cm³ (pressure remaining constant)?

Q 1 (e). The compound Na₂B₄O₇.10H₂O is commonly known as borax. When litmus is added to a solution of borax solution, it turns blue
(i) What can you say about the pH of borax solution?
(ii) Calculate the precentage of boron (B) in borax. (H = 1, B = 11, O = 16, Na = 23. Answer correct to 1 decimal place.) 

Q 1 (f). (i) Sodium hydoxide solution can be used to distinguish between iron (II) sulphate solution and iron (III) sulphate solution because these solution give different coloured precipitates with sodium hydroxide solutions. Give the colour of the precipitate formed with :
(1) iron (II) sulphate solution ;
(2) iron (III) sulphate solution.

(ii) What will you see when barium chloride solution is addded to iron (II) sulphate solution?

(iii) How will the action of dilute hydrochloride acid on sodium carbonate and sodium sulphite enable you to distinguish between these two compounds?

Q 1(g). Choosing only words from the following list write down the appropriate words to fill in the blanks (i) to (v) below :
anions, anode cathode, cations, electrode, electrolyte, nickel, voltameter.

To electroplate an article with nickel requires an (i) ..............................which must be a solution containing (ii)...................... ions. The article to be plated is placed as the(iii).................................. of the cell in which the plating is carried out .The (iv)............................ of the cell is made from pure nickel. The ions which are attracted to the negative electrodes and discharged are called (v) .......................................... .

Q 1(h).The following question result to the Nitrogen Cycle.
(i) What are the soluble nitrogen compounds absorbed by the roots of plants ?
(ii) What kind of plants directly absorb nitrogen from the atmosphere ?
(iii) What term is applied to the conversion of atmosphere nitrogen to useful compounds of nitrogen?
(iv) Compounds such as ammonium nitrate. urea and super - phosphate are used to replace nitrogen and other elements loss from the soil as a result of cultivation. What is the common name given to these compounds ?
(v) What insoluble substance is used in making superphosphate?

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