Introduction: A shadow is a dark area or shape formed when an object blocks light from a source. It is formed due to the absence or obstruction of light.

Explanation:
On the opposite side of the source of light:
- Shadows are formed on the opposite side of the source of light. When light rays hit an object, they get blocked or obstructed by the object, resulting in the formation of a shadow on the opposite side of the object.
- For example, if you place an object in front of a light source such as the sun or a lamp, the shadow will be formed on the surface facing away from the light source.
- This can be observed in our daily lives. When you stand in front of a light source, your shadow appears behind you.

Only on the same side of the source of light:
- This statement is incorrect. Shadows are not formed on the same side of the source of light. If shadows were formed on the same side, they would be blocking the light source itself, which is not possible.
- Shadows are formed when light rays are blocked by an object, creating an area of darkness behind the object.

Only on the walls:
- This statement is incorrect. Shadows can be formed on various surfaces, not just walls. They can be formed on the ground, on objects, or even in the air, depending on the position of the object and the direction of the light source.

Only in the morning:
- This statement is incorrect. Shadows can be formed at any time of the day when there is a source of light and an object blocking the light.
- Shadows may appear longer or shorter depending on the angle of the sun, but they are not limited to only the morning.

Conclusion: The correct statement is that a shadow is formed on the opposite side of the source of light. Shadows are not limited to walls or specific times of the day, but can be formed on various surfaces and at any time when there is a blocking object and a source of light.