Few characteristics of four different metals A, B, C and D are given below: A: Reacts violently with cold water and evolves hydrogen gas. B: Found in nature in free state and does not react with water at any temperature. C:lts oxide is amphoteric in nature. D: Reacts with very dilute nitric acid to evolve H2 gas. A, B, C and D respectively can be O One/More Correct Answer(s)
А. Na, Ag, Al and Mg
В. K, Au, Zn and Mn
C. Mg, Ag, Sn and cu
D. Ca, Cu, Al and Mn
Answers
Answer:
А. Na, Ag, Al, and Mg
В. K, Au, Zn and Mn
Explanation:
Both options A and B are correct.
A) Potassium(K )and Sodium(Na) react violently with cold water and the reaction is highly violent and exothermic where the evolved hydrogen immediately catches fire.
2K(s) + 2H₂O(l) → 2KOH(aq) + H₂ (g) + heat energy
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂ (g) + heat energy
B) Gold(Au) and silver(Ag) are two metals that do not react at all with water. They are very less reactive. In the case of gold, the 6s orbital with one electron is contracted, and this electron is more tightly bound to the nucleus, making it less reactive.
C) Zinc oxide and aluminum oxide is amphoteric because it reacts with both acids and bases to form salts.
D) Manganese(Mn) and Magnesium(Mg) react with dilute nitric acid to evolve H₂ gas
Mn +HNO₃ → Mn(NO₃)₂+H₂
Mg + HNO₃ → Mg (NO₃)₂ + H₂