Answer:
A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
B. Impedes the flow of electrons
Answer:
m = 788.2[kg]
Explanation:
The potential energy of a body is defined as the product of mass by gravitational acceleration by height. And it can be calculated by means of the following equation.

where:
Epot = potential energy = 63405 [J]
m = mass [kg]
g = gravity acceleration = 9.81[m/s²]
h = elevation = 8.2[m]
Now replacing:
![63405=m*9.81*8.2\\m=788.2[kg]](https://tex.z-dn.net/?f=63405%3Dm%2A9.81%2A8.2%5C%5Cm%3D788.2%5Bkg%5D)
Explanation:
hydrogen is primarily produce by steam reforming of natural gas... Methane reacts with steam under 3 -25 bar pressure in the presence of a catalyst to "Produce Hydrogen " , carbon monoxide, and the greenhouse gas carbon dioxide. For steam to proceed, heat must be supplied to the process. Furthermore , new research from Transport & Environment shows that diesel cars not only pollute the air but also emit more climate change emissions (co2) than petroleum gas cars whenever compared to diesel fueled vehicles lifetime. In fact, diesel engines emits 3.65 tonnes of co2 more than a petrol engine equivalent.