The following table shows the tests a ...

ICSE Class 10 Chemistry 2015 Paper

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

ion.

(ii)

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

Copper ion.

(iii)

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

Calcium ion.

(iv)

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

Ammonium ion.

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