Here are the answers to your questions:
Question 1: The tendency of an object to resist a change in motion
Answer: Inertia
Question 2: The act of increasing speed or velocity
Answer: Acceleration
Question 3: The force that attracts any two objects with mass
Answer: Gravitational force
Question 4: Weight
Answer: Mass (though it's important to note that weight is the force exerted by gravity on an object with mass; if this is a trick question asking for the mass-related concept, "Mass" makes sense here)
Question 5: The fundamental law of physics that states that gravitational and inertial forces are of a similar nature and often indistinguishable
Answer: Principle of Equivalence
Question 6: A combination of space and time
Answer: Space-time
Feel free to ask if you have more questions!