Answer:
62.5 %
Explanation:
Let the initial intensity of unpolarized light is Io.
After first polariser the intensity of light becomes I'.
So, 
Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.
According to the law of Malus

Here, Ф = 30 degree

The percentage change in the intensity is given by

= 62.5 %
B. Because they are used to see through objects
A recurring illness or an illness that lasts for a long time. Chronic illnesses are typically very hard to cure.
Answer:
A. change in abiotic factors
Explanation:
Abiotic factors are those factors that have no life, the most important of which can be mentioned: water, temperature, light, pH, soil, humidity, oxygen and nutrients.