Question
Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reaction?
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| Column I | Column II |
| (1) $ZnS$ | (a) Cuprous sulphide |
| (2) $HgS$ | (b) Bauxite |
| (3) $Cu _2 S$ | (c) Zinc blend |
| (4) $Al _2 O _3 \cdot H _2 O$ | (d) Cinnabar |
| (e) Cryolite |