The human activity that impacts the weather on Earth negatively is the burning of fossil fuels. When burning the fossil fuels, the temperature on Earth is increased. This causes Greenhouse Gases. The EPA is trying to cut down on the burning of fossil fuels by closing down power plants ran off of coal.
Answer:
1) rusting of metal is both chemical and physical change
2) black ice is an example of a physical change
Explanation:
when metal rusts, it is due to a reaction between the atoms in the metal and the atoms in the air(oxygen) or water(oxygen). When it rusts it also physically changes the look of the metal from silver to dirty brownish maroon.
Black ice is a change in state hence it cannot be a chemical change as the original substance NO LONGER EXISTS in a chemical reaction. It is a physical change however as the ice is changing into a different state of matter.
HOPE THIS HELPS!!!
Hello!
The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.
We have the following data:
mo (initial mass) = 20 g
m (final mass after time T) = 5 g
x (number of periods elapsed) = ?
P (Half-life) = ? (in minutes)
T (Elapsed time for sample reduction) = 8 minutes
Let's find the number of periods elapsed (x), let us see:
Now, let's find the half-life (P) of the radioactive sample, let's see:
I Hope this helps, greetings ... DexteR! =)
B) differences in temperature
Explanation:
The factor that most directly affects the flow of ocean currents is the differences in ocean temperature from one place to another.
Ocean current is the directional movement of the ocean water in its basin.
The main cause of ocean current is differences in temperature.
- Ocean water on the surface receives direct sunlight.
- This warms and the surface and decreases their density.
- When winds blows over them, they cool and sink under their own weight.
- The less cold water in depths rise to replace them.
- This exchange of ocean water due to loss and gain of heat cause ocean current.
learn more:
Ocean density brainly.com/question/6760255
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Answer:
D
Explanation:
In a Helium (He) atom, the atomic structure of the atom has 2 protons, 2 electrons and 2 neutrons. For an element X to be a Helium (He) atom, it must possess 2 protons. The number of neutrons present will determine its stability either if its probably radioactive or a natural occurring inert gas.
In option 1,
We have H-2. The symbol "H" is used to denote the element hydrogen in the periodic table and hydrogen has only 1 protons and 1 neutron making its mass number 2.
Option 2,
He -2 : here in this option, we have a helium atom, but with mass number of 2 only. Judging from the formula of mass number = protons + neutrons, we already have proton as 2, hence the number of neutrons there is zero (0)
Option 3,
He - 3 : just like in option 2, the only difference here is that the mass number is 3 hence making the number of neutrons just 1.
Option 4,
He - 4 : This option met the requirements of having 2 protons and 2 neutrons making a total of 4 which corresponds to the mass number.
