Correct order of density is-

Options

A. `Li gt Na`
B. `K gt Na`
C. `Mg gt Ca`
D. `Cs lt Rb`

Answer

To determine the correct order of density for alkali and alkaline earth metals, we will analyze the densities of the metals in each group.

### Step 1: Identify the Alkali Metals
The alkali metals are found in Group 1 of the periodic table. The order of density for alkali metals from lowest to highest is:
- Lithium (Li)
- Sodium (Na)
- Potassium (K)
- Rubidium (Rb)
- Cesium (Cs)

### Step 2: Identify the Alkaline Earth Metals
The alkaline earth metals are found in Group 2 of the periodic table. The order of density for alkaline earth metals from lowest to highest is:
- Calcium (Ca)
- Magnesium (Mg)
- Beryllium (Be)
- Strontium (Sr)
- Barium (Ba)
- Radium (Ra)

### Step 3: Compare Densities
Now, we will compare the densities of the metals from both groups:
- For alkali metals: Li < Na < K < Rb < Cs
- For alkaline earth metals: Ca < Mg < Be < Sr < Ba < Ra

### Step 4: Analyze the Given Options
We need to analyze the options provided in the question. The correct statements regarding the densities are:
1. Magnesium (Mg) has a greater density than Calcium (Ca).
2. Lithium (Li) has a lower density than Sodium (Na).
3. Potassium (K) has a lower density than Sodium (Na).

### Step 5: Conclusion
From the analysis, the correct order of density is:
- Calcium (Ca) < Magnesium (Mg)

Thus, the correct option is option number C.

### Final Answer
The correct order of density is:
**Calcium (Ca) < Magnesium (Mg)**

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