Which of the following metals reacts with cold water?
A. Iron
B. Copper
C. Sodium
D. Silver
Answer: Option C
Solution (By JKExamLibrary)
The reactivity of metals with water depends on their position in the reactivity series. Sodium and potassium are highly reactive alkali metals that react vigorously and exothermically with cold water to form hydroxides and hydrogen gas. Iron reacts only with steam, while copper and silver do not react with water.
Explanation:
In Fe₂O₃, oxygen has valency 2. Two Fe atoms combined with three O atoms: total negative charge = 6. For two Fe, total positive = 6, so each Fe has +3. Valency = 3 (ferric). In FeO, valency is 2 (ferrous).
Explanation:
Dalton proposed that all atoms of a given element are identical in mass and properties. The discovery of isotopes (atoms of same element with different mass) contradicted this. Dalton's theory explained the three laws of chemical combination. Later models modified the theory. Subatomic particles and radioactivity also could not be explained by Dalton.
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