Answer:
Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides—produced from power plants and automobiles—the rain becomes much more acidic. Typical acid rain has a pH value of 4.0.
Explanation:
keep smiling (θ‿θ)
I would say that it's C. Seasonal temperatures have dipped over time, but I could easily be wrong, since it's my opinion. A weather condition is defined as the atmospheric conditions that 'comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation. But I believe it could just as easily be B. 150mm of rainfall is a normal average in the city.
Answer: physical
Explanation: freezing and melting are physical changes.
Answer:
When an atom attracts extra electrons it becomes a negative ion. The negative ion is larger than the original atom. The positive nucleus remains the same, with the same attractive force. However, this attractive force is now pulling on more electrons and therefore has less effect.
Or
Positive ions are formed by removing one or more electrons from the outermost region of the atom. The opposite is true of negative ions. When electrons are added to form an anion, the increased electron-electron repulsions cause the electrons to spread out more in space. Thus, anions are larger than their parent atoms.