Question

Give reasons for the following :
(a) Aluminium is a reactive metal but is still used for packing food articles.
(b) Calcium starts floating when water is added to it


CBSE Class X Science SA 2 (3 Marks)

Answer 1

(a) Because it has a great affinity for oxygen and so there is a shining coating of aluminium oxide on the foil which is stable.
 
(b) Calcium floats over water because the bubbles of hydrogen gas formed stick on the surface of the metal.

Answer 2

Answer:

(a) Because it has a great affinity for oxygen and so there is a shining coating of aluminium oxide on the foil which is stable.

 

(b) Calcium floats over water because the bubbles of hydrogen gas formed stick on the surface of the metal.