Answer:
The general equation of the circle is,
x2 + y2 + 2gx + 2fy + c = 0
Radius,
r = 
The equation of the circle which is concentric to the given circle and touches y-axis.
The centre of the circle remains the same and the y-axis will be tangent to the circle.
Point of contact will be (0, 3)
Radius = 2
Equation of the circle:
(x – 2)2 + (y – 3)2 = (2)2
x2 + 4 – 4x + y2 + 9 – 6y = 4
x2 + y2 – 4x – 6y + 9 = 0