Answer:
A. Both describe ways a solid can change.
Answer:
D. A compound can be separated into two or more elements through a chemical reaction.
Explanation:
By method of elimination, we are going t obtain the correct option.
A. A compound is made up of a single atom.
This is wrong because, a compound can contain more than one atom. An example is H2O
B. A compound is made up of many atoms that are all the same type.
This is wrong because a compound can contain atoms of different elements. An example is H2O. It contains atoms of hydrogen and oxygen.
C. A compound can be separated into two or more elements through physical processes.
This is wrong. H2O being a compound cannot be separated by ordinary physical means.
D. A compound can be separated into two or more elements through a chemical reaction.
This is the correct option.
Answer:
Adding a catalyst - More collisions every second and more collisions with enough energy to break bonds.
Increase in pressure - more collisions every second
Increase in temperature - more collisions every second with enough energy to break bonds
Explanation:
According to the collision theory, chemical reaction occurs as a result of collision between reacting particles. Only particles that possess energy above the activation energy of the reaction can collide and result in product formation. Collision of particles having energy less than the activation energy merely result in elastic collisions.
Adding a catalyst lowers the activation energy of the reaction. If the activation energy is lowered, more reactants collide and more of those collisions now have enough energy to break bonds.
When the temperature is increased, the particles become more energetic hence more collisions with energy to break bonds occur.
Increase in pressure brings the reactant particles into close proximity hence more collisions occur.
