Answer: When a substance is pure, it is composed of one type of molecule. For example, table salt is only composed of (more or less) salt molecules, while seawater has water and salt molecules. A more complicated example of a non - pure substance is soil. It has many different types of nutrients and compounds.
Answer:
Light travels in a straight line until it strikes an object.
As white light passes through a prism , it bends and separates into different colors
Answer: -
The acceleration due to gravity at height r = a = GM/r²
Rearranging
r² = GM /a
= (6.674 x 10⁻¹¹ x 5.972 x 10²⁴ ) / 5
r = 8.917 x 10⁶ m
r = 8917 Km
Now Radius of earth = 6371 Km
So height = 8917 - 6371 = 2546 Km
g - Measurement of Mass
m² - Measurement of Area
m³ - Measurement of Volume
km- Measurement of Length
