The following table shows the tests a student performed on four different aqueous solution which are X, Y, Z and W . Based on the observations provided, identify the cation present : Chemical test Observation Conclusion To solution {X}, ammonium hydroxide is added in minimum quantity first and then in excesss. A dirty white precipitate is formed which dissolves in excess to form a clear solution. (i) To solution {Y} ammonium hydroxide is added in minimum quantity first and then in excess. A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution. (ii) To solution {W} a small quantity of sodium hydroxide solution is added and then in excess. A white precipitate is formed which remains insoluble. (iii) To a salt {Z} calcium hydroxide solution is added and then heated. A pungent smelling gas turning moist red litmus paper blue is obtained. (iv)

ICSE Class 10 Chemistry 2015 Solved Paper - Question 56

Question : 56 of 85

Marks: +1, -0

The following table shows the tests a student performed on four different aqueous solution which are

X, Y, Z

and

W

. Based on the observations provided, identify the cation present :

Chemical test	Observation	Conclusion
To solution ${X}$ , ammonium hydroxide is added in minimum quantity first and then in excesss.	A dirty white precipitate is formed which dissolves in excess to form a clear solution.	(i)
To solution ${Y}$ ammonium hydroxide is added in minimum quantity first and then in excess.	A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution.	(ii)
To solution ${W} a$ small quantity of sodium hydroxide solution is added and then in excess.	A white precipitate is formed which remains insoluble.	(iii)
To a salt ${Z}$ calcium hydroxide solution is added and then heated.	A pungent smelling gas turning moist red litmus paper blue is obtained.	(iv)

Solution:

(i)

{\X}= {\Zn}^{++}= {\Zinc}

ion.
(ii)

{\Y}= {\Cu}^{++}=

Copper ion.
(iii)

{\Z}= {\Ca}^{++}=

Calcium ion.
(iv)

{\W}= {\NH}_4^{+}=

Ammonium ion.

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