A nuclear decay is expressed as '_.(6)C^(11) rarr ._(5)B^(11)+beta^(+)+X`
Then the unknown particle `X` is

Options

A. neutron
B. antineutrino
C. proton
D. neutrino

Answer

To determine the unknown particle \(X\) in the nuclear decay reaction:

\[ _{6}^{11}C \rightarrow _{5}^{11}B + \beta^{+} + X \]

we will follow these steps:

### Step 1: Identify the particles involved
In the reaction, we have:
- Carbon-11 (\( _{6}^{11}C \))
- Boron-11 (\( _{5}^{11}B \))
- A positron (\( \beta^{+} \))
- An unknown particle \(X\)

### Step 2: Apply conservation of charge
The total charge before and after the decay must be equal.

- The charge of carbon-11 is \(+6\).
- The charge of boron-11 is \(+5\).
- The charge of a positron (\( \beta^{+} \)) is \(+1\).
- Let the charge of the unknown particle \(X\) be \(z\).

Setting up the equation for charge conservation:

\[ 6 = 5 + 1 + z \]

### Step 3: Solve for \(z\)
From the charge conservation equation:

\[ 6 = 6 + z \implies z = 0 \]

This means that the unknown particle \(X\) has a charge of \(0\).

### Step 4: Apply conservation of atomic mass
Next, we apply conservation of atomic mass:

- The atomic mass of carbon-11 is \(11\).
- The atomic mass of boron-11 is \(11\).
- The atomic mass of the positron is \(0\).
- Let the atomic mass of the unknown particle \(X\) be \(A\).

Setting up the equation for atomic mass conservation:

\[ 11 = 11 + 0 + A \]

### Step 5: Solve for \(A\)
From the atomic mass conservation equation:

\[ 11 = 11 + A \implies A = 0 \]

This means that the unknown particle \(X\) has an atomic mass of \(0\).

### Step 6: Identify the unknown particle
Since \(X\) has both a charge of \(0\) and an atomic mass of \(0\), it can be identified as a neutrino. In beta plus decay, a neutrino is emitted along with the positron.

Thus, the unknown particle \(X\) is a **neutrino**.

### Final Answer
The unknown particle \(X\) is a **neutrino**.

---