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1999 WAEC Chemistry Practical (a) List two gases in each case which; (i) can be used to demonstrate the...

Chemistry
WAEC 1999

(a) List two gases in each case which;

(i) can be used to demonstrate the fountain experiment;

(ii) decolourize acidified potassium tetraoxomanganate (VII).

(b) State briefly how you would distinguish between

(i) crystals of PbCO\(_3\) and Pb(NO\(_3\)) using heat;

(ii) solutions of NH\(_4\)CI and NaCl using litmus paper.

(c) Mention two changes that would be observed on adding moderately concentrated hydrochloric acid to iron filings

 

 

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Explanation

(a)(i) NH\(_3\) or HCl or SO\(_2\) (any two)

(i) H\(_2\)S, SO\(_2\), C\(_2\)H\(_4\), C\(_2\)H\(_2\) etc.(any two)

 

(b)(i) On heating PbCO\(_3\) decomposes giving a colourless, odourless gas

- and yellow residue Pb(NO\(_3\))\(_2\) decomposes giving brown fumes and yellow residue.

(ii) BH\(_4\)Cl\(_{(aq)}\) turns blue litmus paper red NaCl\(_{(aq)}\) has no effect on litmus paper

 

(c) Effervescence/gas evolved. Green solution or gas evolved, iron filings dissolved to give a green solution


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