Answer:
<em>The tyres of car wear out gradually, due to the frictional force. Frictional force arises between two objects when they move over one another. In the given cases it arises between the tyre and the surface which it is travelling on.</em>
Answer:
D, Cholera and Dysentery
Explanation:
Colds travel through contact and air. Tetanus infects through metal.
Answer:
Because the green bacteria produced oxygen during photosynthesis, the purple bacteria had a harder time surviving.
Explanation:
Sample Answer
B is the answer if not B then C
The first three answers are natural changes, while the last three are because of human intervention.
