Explanation:
Coal is a fossil fuel and is the altered remains of prehistoric vegetation. The energy we get from coal today comes from the energy that plants absorbed from the sun millions of years ago. In the burning process of coal, carbon dioxide (CO2) is emitted. Humans expel CO2, and plants utilize it every single day. Carbon is a building block for all forms of life and is used in a lot of everyday products.
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands—called coal forests—that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times. However, many significant coal deposits are younger than this and originate from the Mesozoic and Cenozoic eras.
Answer:
Volume, 
Explanation:
Given that,
The diameter of a human cell is 11 μm
It is enclosed by a membrane that is 4,4 nm thick.
We need to find the volume of the cell. The cell is spherical in shape. The volume of a sphere is given by the formula as follows :

r is the radius of the sphere, r = 5.5 μm
So,

So, the volume of the cell is
.
Answer:
116.67 km/h
Explanation:
avarge speed = total distance / total time
Answer: 490 / 4.2 = 116.67 km/h
Answer:
Option b
Explanation:
The formula of momentum is 
where p is the momentum , m is the mass in kg and v is the velocity in m/s, so
a) momentum is

b) momentum is

c) momentum is
here since the rock is sitting on top of a hill which means the object is stationary or in other words the object is at rest, which means if an object is at rest the velocity is 0m/s so momentum is zero of a stationary object because

d) momentum is

so the highest momentum is in part b which is 12 so option b is our answer.
50.0 becuz it is rounded to 0 which gives the answer a right angle for 223.323 which is N x S