Which of the following has smaller size

Options

A. H
B. `He^(+)`
C. `H^(-2)`
D. `Li^(2+)`

Answer

To determine which of the given ions or atoms has a smaller size, we can follow these steps:

### Step 1: Understand the Concept of Ionic Size
The size of an ion is influenced by its charge. Generally, as the positive charge of an ion increases, the size of the ion decreases. This is because a higher positive charge pulls the electrons closer to the nucleus, resulting in a smaller radius.

### Step 2: Compare the Charges of the Ions
If we are given a list of ions, we need to compare their charges. For example, if we have ions like Na⁺, Mg²⁺, and Al³⁺, we can see that:
- Na⁺ has a +1 charge.
- Mg²⁺ has a +2 charge.
- Al³⁺ has a +3 charge.

### Step 3: Apply the Trend
Based on the trend that higher positive charges lead to smaller ionic sizes, we can conclude:
- Al³⁺ will be smaller than Mg²⁺.
- Mg²⁺ will be smaller than Na⁺.

### Step 4: Conclusion
From the comparison, we can conclude that Al³⁺ has the smallest size among the ions listed.

### Final Answer
The ion with the smallest size is Al³⁺.

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