Arrange the following in increasing order of basic strength :
`MgO,SrO,K_(2)O,NiO,Cs_(2)O`

Options

A. `MgO lt SrO lt K_(2)O lt NiO lt Cs_(2)O`
B. `Cs_(2)O lt K_(2)O lt MgO lt SrO lt NiO`
C. `NiO lt MgO lt SrO lt K_(2)O lt Cs_(2)O`
D. `K_(2)O lt NiO lt MgO lt SrO lt Cs_(2)O`

Answer

To arrange the compounds MgO, SrO, K₂O, NiO, and Cs₂O in increasing order of basic strength, we will analyze the basicity based on periodic trends in the s-block elements.

### Step-by-Step Solution:

1. **Identify the Group and Period**:
- MgO (Magnesium oxide) - Group 2
- SrO (Strontium oxide) - Group 2
- K₂O (Potassium oxide) - Group 1
- NiO (Nickel oxide) - Transition metal oxide (not in s-block)
- Cs₂O (Cesium oxide) - Group 1

2. **Understand Basic Strength Trends**:
- Basic strength generally increases down a group in the periodic table due to the increasing size of the cation, which makes it easier to donate electrons.
- Basic strength generally decreases across a period from left to right due to increasing electronegativity.

3. **Analyze Each Compound**:
- **Cs₂O**: Cesium is at the bottom of Group 1, making it very basic.
- **K₂O**: Potassium is above cesium in Group 1, so it is less basic than Cs₂O.
- **SrO**: Strontium is below magnesium in Group 2, making it more basic than MgO.
- **MgO**: Magnesium is above strontium in Group 2, making it less basic than SrO.
- **NiO**: Nickel oxide is a transition metal oxide and is generally less basic than alkaline earth and alkali metal oxides.

4. **Arrange in Increasing Order**:
- The order of basic strength from least to most basic is:
- NiO < MgO < SrO < K₂O < Cs₂O

### Final Answer:
**Increasing order of basic strength**: NiO < MgO < SrO < K₂O < Cs₂O