Question

Which of the following alkali metals has the highest melting point?

• A. $\mathrm{K}$
• B. $\mathrm{Li}$
• C. $\mathrm{Na}$
• D. $\mathrm{Rb}$

Answer 1

The correct option is B

$\mathrm{Li}$

Explanation of correct answer

1. Among alkali metals, Li has the greatest melting point.
2. The M.P. of all alkali metals is very low. The melting point of elements lowers as they progress through the periodic table, from Li to Rb.

Explanation of incorrect answer

Option (A) $\mathrm{K}$

Potassium metal is a soft, white metal with a silvery sheen that has a low melting point and is an excellent heat and electricity conductor.

Option (C) $\mathrm{Na}$

Sodium is a silvery-white soft metal. The most common alkali metal is sodium.

Option (D) $\mathrm{Rb}$

Rubidium, on the other hand, is more broadly distributed and is rarely discovered as a native mineral; it only occurs as an impurity in other minerals.

Final Answer: The correct option is B.