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Subject :NSO    Class : Class 8

An unknown metal X when placed in copper sulphate solution, red brown pieces of copper fall to the bottom of the test tube. When metal X is placed in aluminium sulphate solution, no change is observed. Metal X can be

A Sodium
B Potassium
C Iron
D Calcium.

it will be calcium as ,iron is below aluminium in the reactivity series and the metal 'X' is more reactive than Al. as K

Ans 1:

Class : Class 8

Ans 2:

Class : Class 9
according to reactivity series K>Na>Ca>Mg>Al>Zn>Fe>Pb>H>Cu>Hg>Ag>Au>Pt the metal should be between Al and Cu and hence Fe is the answer

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