The increasing order of the density of the alkali metal is

Options

A. `Li lt Nalt K lt Rb lt Cs`
B. `Cs lt Rb lt K lt Na lt Li`
C. `Li lt Klt Na lt Rb lt Cs`
D. `K lt Na ltLiltRbltCs`

Answer

To determine the increasing order of density of alkali metals, we will analyze the properties of the alkali metals in Group 1 of the periodic table, which include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

### Step-by-Step Solution:

1. **Identify the Alkali Metals**:
The alkali metals in the periodic table are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

2. **Understand Density**:
Density is defined as mass per unit volume (Density = Mass/Volume). In general, as we move down a group in the periodic table, the atomic mass increases, and the atomic volume also increases. However, the increase in volume can sometimes be more significant than the increase in mass.

3. **Trends in Alkali Metals**:
- As we move down the group from lithium to cesium, the atomic mass increases.
- However, the atomic volume also increases, but not in a linear manner due to the increasing size of the atoms.

4. **Density Order**:
- Lithium has the lowest density among the alkali metals due to its small mass and volume.
- Sodium has a higher density than lithium.
- Potassium has an unusual case where its density is less than that of sodium despite its larger atomic mass. This is due to the larger atomic volume of potassium.
- Rubidium has a higher density than potassium.
- Cesium has the highest density among the alkali metals.

5. **Correct Increasing Order**:
Based on the above analysis, the correct increasing order of density for alkali metals is:
- Lithium (Li) < Potassium (K) < Sodium (Na) < Rubidium (Rb) < Cesium (Cs)

### Final Answer:
The increasing order of density of alkali metals is:
**Li < K < Na < Rb < Cs**