Answer:
c
Explanation:
The changing of color of a substance is not necessarily an indicator of a chemical change. For example, changing the color of a metal does not change its physical properties. However, in a chemical reaction, a color change is usually an indicator that a reaction is occurring.
I can answer the first question: Water rises because of the sun's heat and turns into water vapor. After that, it gathers up and forms a cloud. When the cloud is filled enough with vapor, precipitation occurs.
Answer:
The magnitude of force is 
Solution:
As per the question:
The strength of Electric field due west at a certain point, 
Charge, Q = - 6 C
Now, the force acting on the charge Q in the electric field is given by:


Here, the negative sign indicates that the force acting is opposite in direction.