The order of reactivity of K, Mg, Au and Zn with water is

Options

A. `K gt Zn gt Mg gt Au`
B. ` K gt Mg gt Zn gt Au`
C. `K gt Au gt Mg gt Zn`
D. `Au gt Zn gt K gt Mg`

Explanation

To determine the order of reactivity of Potassium (K), Magnesium (Mg), Gold (Au), and Zinc (Zn) with water, we can refer to the electrochemical series (also known as the reactivity series). Here’s the step-by-step solution:

### Step 1: Understand the Reactivity Series
The reactivity series is a list of metals arranged in order of decreasing reactivity. The more reactive a metal is, the more readily it will react with water and other substances.

### Step 2: Identify the Metals and Their Reactivity
From the electrochemical series, we can identify the relative reactivity of the metals in question:
- Potassium (K) is highly reactive.
- Magnesium (Mg) is moderately reactive.
- Zinc (Zn) is less reactive than magnesium.
- Gold (Au) is one of the least reactive metals.

### Step 3: Order the Metals Based on Reactivity
Based on the information from the reactivity series:
1. Potassium (K) - most reactive
2. Magnesium (Mg) - next in reactivity
3. Zinc (Zn) - less reactive than magnesium
4. Gold (Au) - least reactive

Thus, the order of reactivity with water is:
**K > Mg > Zn > Au**

### Step 4: Match with Given Options
Now, we need to match this order with the given options:
- Option A: K > Zn > Mg > Au
- Option B: K > Mg > Zn > Au
- Option C: K > Au > Mg > Zn
- Option D: Au > Zn > K > Mg

The correct option that matches our order (K > Mg > Zn > Au) is **Option B**.

### Final Answer
The order of reactivity of K, Mg, Au, and Zn with water is:
**K > Mg > Zn > Au** (Option B)

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