Which of these statements best describes a double-replacement reaction? An element takes the place of another element in a compound.

Two or more substances react to form a single substance.

One compound breaks down into two or more simpler substances.

Two different compounds exchange positive ions and form two new compounds.

James is trying to prove newton's 2nd law of motion. he tries to move four different objects with different masses, shapes, and sizes from point a to point b. the objects are a toy car, a car, a refrigerator, and a kitchen table. after some experimentation, he finds that force is dependent on the mass of the object, rather than it's size or shape. the object that takes the most force to move is the

What will a positive and a negative charge do if they are separated from each other?

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid