Alkali metlas have

Options

A. high melting and boiling point
B. low melting and boiling point
C. high melting and low boiling point
D. low melting and high boiling point

Answer

### Step-by-Step Solution

1. **Identify Alkali Metals**: Alkali metals are the elements found in Group 1 of the periodic table. This group includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

2. **Properties of Alkali Metals**: Alkali metals are characterized by having a single electron in their outermost shell. This single valence electron contributes to their chemical reactivity and properties.

3. **Size of Alkali Metals**: Alkali metals have relatively large atomic sizes compared to other elements. As you move down the group from lithium to francium, the size of the atoms increases.

4. **Melting and Boiling Points**: Due to their larger atomic size, alkali metals have low melting and boiling points. The larger size leads to weaker metallic bonds, which require less energy to break.

5. **Metallic Bonding**: The metallic bonds in alkali metals are weak because of the large atomic size and the presence of only one valence electron. This weak bonding contributes to the low melting and boiling points of these metals.

6. **Conclusion**: Therefore, the correct statement regarding alkali metals is that they have low melting and boiling points due to their weak metallic bonds.