Answer:
The acidic or the basic nature of a substance can be determined using a pH indicator. If the pH indicator , shows a pH value less than 7 , the substance is acidic. Lower the pH , high is the acidic nature.
Explanation:
2 mins for sure depending on the distance for walking
An uncharged body is a body that has equal magnitude of positive as well as negative charge on it. So as soon as some charged body is placed near it, the charged body induces negative charges on the uncharged body.
The light gathering of a telescope goes as the area of the telescope, therefore as the square of the aperture:

where D is the aperture of the telescope.
Therefore, using D1=8 m and D2=2 m, we find

So, the larger telescope will collect 16 times more light than the smaller one.