Consider four beakers labeled A, B, C, and D, each containing an aqueous solution and a solid piece of metal. Identity the beakers in which a chemical reaction will occur and those in which no reaction will occur. Mn(s) Ca(NO3)2(aq) KOH(aq) Fe(s) Pt(NO3)2(aq) Cu(s) Cr(s) H2SO4(aq)

1. Mn(s) + Ca(NO₃)₂(aq)  > No reaction

2. KOH(aq) +  Fe(s)   > No reaction

3. Pt(NO₃)₂(aq) + Cu(s)  > Reaction occurs

4. Cr(s) + H₂SO₄(aq)   > Reaction occurs

Explanation:

The activity series of metals is a series that arranges metals in order of reactivity from highest to lowest. It is used to determine which metal will displace another in a single displacement reactions, whereby a metal A, will replace or be replaced by another metal B in an aqueous solution depending on their relative positions in the activity series.

Considering the given reactions:

1. Mn(s) + Ca(NO₃)₂(aq)

2. KOH(aq) +  Fe(s)

3. Pt(NO₃)₂(aq) + Cu(s)

4. Cr(s) + H₂SO₄(aq)

Reaction 1 will not occur because manganese, Mn, is lower than calcium, Ca, in the activity series of metals and cannot displace it from aqueous solutions.

Reaction 2 will not occur since iron, Fe, is lower than potassium, K, in the activity series and cannot displace it from aqueous solutions.

Reaction 3 will occur since platinum, Pt, is lower than copper, Cu, in the activity series and thus can be displaced by copper from aqueous solutions.

Reaction 4 will  occur since chromium, Cr, is higher than hydrogen, H, in the activity series and thus, can displace it from aqueous solutions.