Samples of four metals A, B, C and D were taken and were added to the following solutions one by one.
The results obtained have been tabulated as follows :
`{:("Metal",,"Solution to which metal is added",,),(,"Iron(II) sulphate","Copper(II) sulphate","Zince sulphate","Silver nitrate"),("A","No reaction","Displacement"," __"," __"),("B","Displacement"," __","No reaction"," __"),("C","No reaction","No reaction","No reaction","Displacement"),("D","No reaction","No reaction","No reaction","No reaction"):}`
Use the table given above to answer the following questions :
(a) Which is the most reactive metal ?
(b) What would you observe when B is added to solution of copper(II) sulphate ?
(c ) Arrange the metals A, B, C and D in order of increasing reactivity.

Explanation

To solve the problem, we will analyze the given observations for metals A, B, C, and D when added to various metal sulfate solutions. We will determine the most reactive metal, the observation when metal B is added to copper(II) sulfate, and arrange the metals in order of increasing reactivity.

### Step-by-Step Solution:

1. **Identify the Observations**:
- Metal A:
- Iron(II) sulfate: No reaction
- Copper(II) sulfate: Displacement
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