Pick out the chemically most reactive elements from the given triads.
Li,Na,K and F,Cl,Br

Options

A. Li & F
B. Na and Cl
C. K and Br
D. K and F

Explanation

To solve the question of identifying the chemically most reactive elements from the given triads (Li, Na, K and F, Cl, Br), we can follow these steps:

### Step 1: Understand the Reactivity of Alkali Metals
- The first triad consists of alkali metals: Lithium (Li), Sodium (Na), and Potassium (K).
- Alkali metals are known for their reactivity, which increases as you move down the group in the periodic table. Therefore, among Li, Na, and K, Potassium (K) is the most reactive.

### Step 2: Understand the Reactivity of Halogens
- The second triad consists of halogens: Fluorine (F), Chlorine (Cl), and Bromine (Br).
- Halogens are also known for their reactivity, which decreases as you move down the group in the periodic table. Hence, among F, Cl, and Br, Fluorine (F) is the most reactive.

### Step 3: Conclusion
- From the analysis, we find that the most reactive element in the first triad is Potassium (K) and in the second triad is Fluorine (F).
- Therefore, the chemically most reactive elements from the given triads are Potassium (K) and Fluorine (F).

### Final Answer:
- The most reactive elements are **Potassium (K)** and **Fluorine (F)**.

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