Amongest the following elements, how many occurs in the earth's crust in the native state ?
`Au,Pt,Hg,Zn,Fe`.

Explanation

To determine how many of the given elements occur in the Earth's crust in their native state, we need to analyze the reactivity of each element listed: Au (Gold), Pt (Platinum), Hg (Mercury), Zn (Zinc), and Fe (Iron).

### Step-by-Step Solution:

1. **Identify the Elements**: The elements provided are:
- Au (Gold)
- Pt (Platinum)
- Hg (Mercury)
- Zn (Zinc)
- Fe (Iron)

2. **Understand the Concept of Native State**:
- Native state refers to elements that are found in their pure, metallic form in nature, rather than as compounds or ores.
- Typically, metals that are less reactive are more likely to be found in their native state.

3. **Analyze Each Element**:
- **Au (Gold)**: Gold is a noble metal and is highly unreactive. It is commonly found in its native state.
- **Pt (Platinum)**: Platinum is also a noble metal with very low reactivity, and it can be found in its native state.
- **Hg (Mercury)**: Mercury is less reactive compared to many other metals and can also be found in its native state.
- **Zn (Zinc)**: Zinc is more reactive and typically found in the form of ores (like zinc oxide or zinc sulfide), not in its native state.
- **Fe (Iron)**: Iron is quite reactive and usually found in ores (like hematite or magnetite), not in its native state.

4. **Count the Elements in Native State**:
- From the analysis, the elements that occur in the native state are:
- Au (Gold)
- Pt (Platinum)
- Hg (Mercury)
- Therefore, there are **3 elements** that occur in the Earth's crust in the native state.

### Final Answer:
**3 elements (Au, Pt, Hg) occur in the Earth's crust in the native state.**