Run off
Explanation:
Run-off are the water sources that becomes polluted as they travel over the earth surface.
Surface run-off are water that moves on the earth surface. This water is a component of the water cycle which usually originate from precipitation.
- As the water moves through different terrain it comes into contact with different pollutants.
- Some of these run-off travels through mines, waste disposal sites among others.
- This leads to the contamination of this form of water as it moves through these earth materials.
- They are the most polluted water
Learn more:
Ocean water brainly.com/question/6760255
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Answer:
Option B is correct.
4
Explanation:
We know that an atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example, if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,
Number of neutrons + number of proton
2 + 2 = 4
Thus, option B is correct.
3. B
4. A
5.A
6. A (i think)
Hope this helps
