The correct answer is A: H3PO4
The average radius(r) of each grain is r = 50 nanometers
= 50*10^-6 meters
Since it is spherical, so
Volume=(4/3)*pi*r^3
V= (4/3)*pi*(50*10^-6)^3
V=5.23599*10^-13 m^3
We are given the Density(ρ) =2600kg/m^3
We know that:
Density(p) = mass(m)/volume(V)
m = ρV
So the mass of a single grain is:
m = 5.23599*10^-13 * 2600 = 1.361357*10^-9 kg
The surface area of a grain is:
a = 4*pi*r^2
a = 4*pi*(50*10^-6)^2
a = 3.14*10^-8 m^2
Since we know the surface area and mass of a grain, the
conversion factor is:
1.361357*10^-9 kg / 3.14*10^-8 m^2
Find the Surface area of the cube:
cube = 6a^2
cube = 6*1.1^2 = 7.26m^2
multiply this by the converions ratio to get:
total mass of sand grains = (7.26 m^2 * 1.361357*10^-9 kg)
/ (3.14*10^-8 m^2)
total mass of sand grains = 0.3148 kg = 314.80 g
Correct ones are
- Technical improvements that have made alternative energy sources more practical to use
- Increase in concern for environment.
why?
Fossil fuels are hydrocarbons
- Hydrocarbons on burning with oxygen releases harmful carbon dioxide .
Answer:
Option D is the correct answer.
Explanation:
Stress is the force per unit area that tend to change the shape of body.
Stress is defined as internal resistive force per unit area.
So, so stress distributed over an area is best described as internal resistive force.
Option D is the correct answer.
Answer:
A. Materials with a low index of refraction cause light to refract very little.
