Which one is incorrect among the following statements ?

Options

A. Cells used in wrist warches are button cells .
B. Secondary cells are rechargeable cells .
C. When current is passed through the filament bulb glows .
D. none of these.

Explanation

To determine which statement is incorrect among the given options, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** "The cells used in wristwatches are button cells."

- **Explanation:** This statement is true. Wristwatches typically use button cells, which are small, round batteries that provide power to the watch.

### Step 2: Analyze the Second Statement
**Statement:** "Reversible Chemical Reactions in Secondary Cells."

- **Explanation:** This statement is also true. Secondary cells, or rechargeable batteries, undergo reversible chemical reactions, allowing them to be recharged and used multiple times.

### Step 3: Analyze the Third Statement
**Statement:** "When current is passed through a filament bulb, it will glow."

- **Explanation:** This statement is true as well. When an electric current passes through the filament of a bulb, it heats up and emits light, causing the bulb to glow, provided that the filament is intact.

### Step 4: Analyze the Fourth Statement
**Statement:** "None of these."

- **Explanation:** Since the first three statements are all correct, this implies that the fourth statement, which claims that none of the previous statements are incorrect, is also true.

### Conclusion
After analyzing all the statements, we find that all the first three statements are correct. Therefore, the answer to the question "Which one is incorrect among the following statements?" is:

**Answer:** Option 4: None of these.

---