Three naturally occurring elements X,Y and Z are good conductors of electricity and are very precious. Z is more reactive than X and Y and on exposure to air for a long time turns black. Z forms an alloy with Y and is used in jewellery and X is used as a catalyst. Identify X , Y and Z.

Explanation

To identify the elements X, Y, and Z based on the clues provided, we can follow these steps:

### Step 1: Identify the Characteristics
We know that:
- X, Y, and Z are good conductors of electricity.
- They are precious metals.
- Z is more reactive than both X and Y.
- Z turns black when exposed to air for a long time.
...