The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element ?

Options

A. `""_(15)^(31)X`
B. `""_(16)^(31)X`
C. `""_(15)^(16)X`
D. `""_(16)^(15)X`

Explanation

To determine the correct representation of element X, we need to follow these steps:

### Step 1: Identify the number of electrons
The problem states that the number of electrons in element X is 15. Since the number of electrons is equal to the number of protons in a neutral atom, we can conclude that the atomic number (Z) is 15.

### Step 2: Identify the number of neutrons
The problem also states that the number of neutrons in element X is 16.

### Step 3: Calculate the mass number
The mass number (A) of an element is calculated by adding the number of protons (Z) and the number of neutrons (N):
\[ A = Z + N \]
Substituting the values we have:
\[ A = 15 + 16 = 31 \]

### Step 4: Write the representation of the element
The standard representation of an element is given in the form:
\[ \text{Element Symbol} \, _{Z}^{A} \text{Element Name} \]
Where:
- A is the mass number
- Z is the atomic number

For element X, we have:
- Mass number (A) = 31
- Atomic number (Z) = 15

### Step 5: Identify the element
The element with atomic number 15 is phosphorus (P). Therefore, the correct representation of element X is:
\[ \text{P} \, _{15}^{31} \]

### Final Answer
The correct representation of the element X is \( \text{P} \, _{15}^{31} \).

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