Assertion At the centre of a circular current carrying loop `(I_(1))`, there is an infinitely long straight of the circle. Then magnetic force of attraction between two is zero.
Reason Magnetic field of `I_(1)` at centre is inwards, parallel to `I_(2)`.

Answer

To solve the given question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
The assertion states that at the center of a circular current-carrying loop (I₁), there is an infinitely long straight wire (I₂) along the axis of the circle. The claim is that the magnetic force of attraction between the two is zero.

2. **Understanding the Reason**:
The reason provided states that the magnetic field (B₁) produced by the circular loop at its center is directed inwards and is parallel to the current in the straight wire (I₂).

3. **Magnetic Field at the Center of the Loop**:
The magnetic field at the center of a circular loop carrying current (I₁) is given by the formula:
\[ B = \frac{\mu_0 I}{2R} \]
where \( \mu_0 \) is the permeability of free space and \( R \) is the radius of the loop. The direction of this magnetic field can be determined using the right-hand thumb rule, which indicates that it is directed into the plane of the loop.

4. **Direction of Current in the Straight Wire**:
If the current in the straight wire (I₂) is directed into the plane of the paper, then it is parallel to the magnetic field produced by the circular loop (B₁).

5. **Force on the Straight Wire**:
The force experienced by a current-carrying conductor in a magnetic field is given by:
\[ F = I \cdot L \cdot B \cdot \sin(\theta) \]
where \( \theta \) is the angle between the direction of the current and the magnetic field. Since the magnetic field (B₁) and the current (I₂) are parallel, \( \theta = 0° \) and hence:
\[ \sin(0°) = 0 \]
Therefore, the force \( F \) becomes:
\[ F = I \cdot L \cdot B \cdot 0 = 0 \]

6. **Conclusion**:
Since the magnetic force of attraction between the circular loop and the straight wire is indeed zero, the assertion is correct. The reason provided also correctly explains why the force is zero.

Thus, both the assertion and reason are true, and the reason is the correct explanation for the assertion.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation for the assertion.