When zinc is added to AgNO$_{3}$ solution, crystals of silver forms on the zinc surface. This indicates that zinc is

Analyze the question: Zinc is placed in silver nitrate solution, and silver crystals form on the zinc. We need to say what happens to the zinc.

Concept: This is a displacement (redox) reaction. A more reactive metal displaces a less reactive metal from its salt solution.

• Oxidation = loss of electrons (oxidation number increases)
• Reduction = gain of electrons (oxidation number decreases)

In the reactivity series, zinc is above silver, so zinc is more reactive and displaces silver.

Solution:

Overall equation: Zn(s) + 2AgNO₃(aq) → Zn(NO₃)₂(aq) + 2Ag(s)

Half-equations:

• Zn → Zn²⁺ + 2e⁻ (zinc loses electrons, so it is oxidised)
• Ag⁺ + e⁻ → Ag (silver ions gain electrons, so they are reduced, forming the silver crystals)

Zinc's oxidation number goes from 0 to +2, which confirms oxidation. Zinc is also the reducing agent, because it supplies the electrons that reduce Ag⁺.

Checking the options:

• A. Oxidised: correct, since zinc loses electrons.
• B. Reduced: this is what happens to silver ions, not zinc.
• C. Decomposed: zinc is an element and does not break down into simpler substances.
• D. Dissociated: this applies to ionic compounds splitting into ions in solution, not to a metal reacting.

Answer: A. oxidised

Tip: Use OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons). When a metal dissolves into solution as ions, it has been oxidised. The metal that appears as a deposit, here silver, has been reduced from its ions.