1. Identify the group 14 elements from the given atomic numbers

Group 14 elements are:

• $6 \rightarrow \text{C}$ (Carbon)
• $14 \rightarrow \text{Si}$ (Silicon)
• $50 \rightarrow \text{Sn}$ (Tin)
• $82 \rightarrow \text{Pb}$ (Lead)

So the options correspond to:

• A: $14 = \text{Si}$
• B: $50 = \text{Sn}$
• C: $6 = \text{C}$
• D: $82 = \text{Pb}$

2. Recall the trend of melting points in group 14

Approximate melting points are:

• Carbon: very high melting/sublimation point
• Silicon: very high melting point
• Tin: relatively low melting point
• Lead: low melting point, but higher than tin? Let us compare carefully.

Typical values:

• $\text{C} \approx 3500^\circ \text{C}$ (very high)
• $\text{Si} \approx 1410^\circ \text{C}$
• $\text{Sn} \approx 232^\circ \text{C}$
• $\text{Pb} \approx 327^\circ \text{C}$

3. Find the lowest melting point

Among these: $\text{Sn} (232^\circ \text{C}) < \text{Pb} (327^\circ \text{C}) < \text{Si} < \text{C}$

Hence, the element with the lowest melting point is tin (Sn).

4. Atomic number of tin

Tin has atomic number: $50$

5. Correct option

Therefore, the correct answer is: $\boxed{50}$ which is Option B.

6. Comparison with stored correct answer

Stored correct answer: B

Our derived answer: B

So, the derived answer agrees with the stored answer.