Which of the following symbols are not acceptable ?
(i) `._(35)^(79)Br` (ii) `.^(79)Br`
(iii) `._(79)^(35)Br` (iv) `._(35)Br`

Options

A. `(ii),(iv)`
B. `(iii),(iv)`
C. `(ii),(iii),(iv)`
D. `(ii),(iii)`

Explanation

To determine which of the given symbols are not acceptable, we need to analyze each option based on the standard notation for representing elements in chemistry. The standard notation includes the element's symbol, the mass number (A) as a superscript, and the atomic number (Z) as a subscript.

### Step-by-step Solution:

1. **Understanding the Notation**:
- The correct format for an element is:
\[ \text{Element Symbol} \quad _{Z}^{A} \]
- Where:
- \( A \) = Mass number (number of protons + number of neutrons)
- \( Z \) = Atomic number (number of protons)

2. **Analyzing Each Option**:
- **(i) `._(35)^(79)Br`**:
- Here, \( Z = 35 \) (atomic number of Bromine) and \( A = 79 \) (mass number).
- This is correctly formatted:
\[ \text{Br} \quad _{35}^{79} \]
- **Acceptable**.

- **(ii) `.^(79)Br`**:
- This notation only has the mass number \( A = 79 \) and lacks the atomic number \( Z \).
- The atomic number is essential for clarity.
- **Not Acceptable**.

- **(iii) `._(79)^(35)Br`**:
- Here, \( Z = 79 \) and \( A = 35 \), which is incorrect because the atomic number cannot be greater than the mass number for stable elements.
- The correct order should be \( Z = 35 \) and \( A = 79 \).
- **Not Acceptable**.

- **(iv) `._(35)Br`**:
- This notation has the atomic number \( Z = 35 \) but lacks the mass number \( A \).
- The mass number is necessary for complete identification.
- **Not Acceptable**.

3. **Conclusion**:
- The symbols that are not acceptable are:
- (ii) `.^(79)Br`
- (iii) `._(79)^(35)Br`
- (iv) `._(35)Br`

### Final Answer:
The unacceptable symbols are (ii), (iii), and (iv).

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