Which of the following species has maximum charge to mass ratio?

Options

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

Answer

To find out which species has the maximum charge to mass ratio, we will calculate the charge to mass ratio (e/m) for each of the given species: D⁺, H⁺, He⁺, and He²⁺.

### Step-by-Step Solution:

1. **Identify the Charges and Masses:**
- D⁺ (Deuterium): Charge = +1, Mass = 2 (amu)
- H⁺ (Hydrogen): Charge = +1, Mass = 1 (amu)
- He⁺ (Helium): Charge = +1, Mass = 4 (amu)
- He²⁺ (Helium ion with +2 charge): Charge = +2, Mass = 4 (amu)

2. **Calculate Charge to Mass Ratio for Each Species:**
- For D⁺:
\[ \text{Charge to Mass Ratio} = \frac{Charge}{Mass} = \frac{1}{2} = 0.5 \]
- For H⁺:
\[ \text{Charge to Mass Ratio} = \frac{Charge}{Mass} = \frac{1}{1} = 1 \]
- For He⁺:
\[ \text{Charge to Mass Ratio} = \frac{Charge}{Mass} = \frac{1}{4} = 0.25 \]
- For He²⁺:
\[ \text{Charge to Mass Ratio} = \frac{Charge}{Mass} = \frac{2}{4} = 0.5 \]

3. **Compare the Charge to Mass Ratios:**
- D⁺: 0.5
- H⁺: 1
- He⁺: 0.25
- He²⁺: 0.5

4. **Determine the Maximum Charge to Mass Ratio:**
- The highest value among the calculated ratios is for H⁺, which is 1.

### Conclusion:
The species with the maximum charge to mass ratio is **H⁺**.