Four solutions labelled as W, X, Y and Z have pH values 1, 9, 3 and 13 respectively. Which of the following represents the correct decreasing order of hydrogen ion concentration of these solutions?

Options

A. `Z gt X gt Y gt W `
B. `W gt Y gt Z gt X`
C. `W gt Z gt Y gt X`
D. `W gt Y gt X gt Z`

Answer

To determine the correct decreasing order of hydrogen ion concentration for the solutions W, X, Y, and Z based on their pH values, we can follow these steps:

### Step 1: Understand the pH scale
- The pH scale ranges from 0 to 14, where lower pH values indicate higher hydrogen ion (H⁺) concentrations, and higher pH values indicate lower H⁺ concentrations.

### Step 2: Identify the pH values of the solutions
- W: pH = 1
- X: pH = 9
- Y: pH = 3
- Z: pH = 13

### Step 3: Determine the hydrogen ion concentration
- The hydrogen ion concentration can be calculated using the formula:
\[ [H^+] = 10^{-\text{pH}} \]
- For each solution:
- For W (pH = 1):
\[ [H^+]_W = 10^{-1} = 0.1 \, \text{M} \]
- For X (pH = 9):
\[ [H^+]_X = 10^{-9} \, \text{M} \]
- For Y (pH = 3):
\[ [H^+]_Y = 10^{-3} = 0.001 \, \text{M} \]
- For Z (pH = 13):
\[ [H^+]_Z = 10^{-13} \, \text{M} \]

### Step 4: Compare the hydrogen ion concentrations
- Now we can compare the calculated hydrogen ion concentrations:
- W: 0.1 M
- Y: 0.001 M
- X: \(10^{-9}\) M
- Z: \(10^{-13}\) M

### Step 5: Arrange in decreasing order
- The correct decreasing order of hydrogen ion concentration is:
1. W (0.1 M)
2. Y (0.001 M)
3. X (\(10^{-9}\) M)
4. Z (\(10^{-13}\) M)

### Final Answer
The correct decreasing order of hydrogen ion concentration is: **W > Y > X > Z**.