The answer is A because An Indicator" changes color when it comes in contact with an acid or a base
An indicator could be anything like:
1) Litmus paper
2) Bromothymol blue
3) Phenolphthalein
Answer:
Planets that are farther from the sun than the earth (all but Mercury and Venus) will exhibit retrograde motion.
If the position of the planet is observed relative to the background stars, the planet will appear to move backward relative to the stars when the earth is moving in an Eastward direction faster than the planet, and the planet appears to move backwards relative to the stars
(The planet will be on the side of the earth that is opposite that of the sun)
Answer:

Explanation:
The two cars are under an uniform linear motion. So, the distance traveled by them is given by:

is the same for both cars when the second one catches up with the first. If we take as reference point the initial position of the second car, we have:

We have
. Thus, solving for t:
