The correct answers are:
It is a high tide at one place on Earth, the place exactly opposite to it will have a low tide - False;
When there's a high tide on one place on Earth, than there's a high tide on the exactly opposite place as well. The same goes for the low tide too.
Earth's gravity can act as a slingtshot to boost the velocity of nearby spacecrafts; - False;
Earth' gravity doesn't contribute to increasing the velocity of a spacecraft, but instead it lowers its velocity because it is pulling it downwards.
The Sun, along with the entire solar system, moves around the galaxy - True;
The Sun, along with the solar system, like all the other stars and their systems, are moving around the galaxy, thus they are constantly on the move, despite being seemingly static fro Earth's point of view.
Without gravity, there will be no atmosphere surrounding Earth - True;
If there isn't any gravity, than there will be no atmosphere because the gases will be free to go into the open space.
The mass of an object on Jupiter is greater than its mass on Earth - True;
The mass of an object on Jupiter is greater than its mass on Earth because of the much bigger gravitational pull on Jupiter.
To find the mass of an object, multiply the weight of the object and gravity - False;
The mass of an object can be find with the weight being divided by the acceleration due to gravity.
