Answer: Experiment 1 could be used to check the gravitational mass of an object.
Step-by-step explanation: Gravitational mass can be described as the strength which the gravitational force has on an object when it is present in the gravitational force. An object at rest will experience only the gravitational force. Whereas an object that is pulled along a horizontal surface with a spring scale will have other forces acting on it along with the gravitational force.
To check for the gravitational mass, an object should only have a gravitational force acting upon it. Hence, experiment 1 is the correct option.