A paragraph on acid rain...please no copy and pasted.

Acid rain is quite unusual but very highly corrosive to nature and even kills a lot of vegetation. It is caused when gaseous compounds of ammonium, carbon, nitrogen, and sulphur are released into the atmosphere. Acid rain that seeps into the ground can dissolve nutrients, such as magnesium and calcium, that trees need to be healthy. The ecological effects of acid rain are most clearly seen in aquatic environments, such as streams, lakes, and marshes where it can be harmful to fish and other wildlife.

Explanation:

Several multinational companies close their factories in the nation because of its changing economic climate.

A nation PPC in this case would suffer a consistent loss in the first years, due to the impact of the multinational companies not only in their respective sectos but also in the aftermath. However, it depends on the respond of the nation to this event how the PPC would be affected in the long period. If the nation has a robust and efficient welfare state, it is possible to absorbe the loss quickier than in other cases.

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A mass e-learning initiative makes education cheaper and accessible across the nation.

In this case the PPC would likely increase, due to the fact that the education makes possible for the people to access jobs that are paid better, thus having more power of purchase, with positive repercussion on all the nation, not only from a PPC point of view, but also in the quality of life and in the overall happiness of the nation.

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Government money is illegally taken by increasingly corrupt bureaucrats and politicians.

Corruptions is one of the factor that leads to a loss in the PPC, because much of the economy is hidden from the pubblic, thus it is not affecting the macro-economy of the nation on a statistic base. Corruction however would likely affect the real economy, causing loss of PPC due to lack of jobs, influence on the market and so on.

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New economic policies facilitate the signing of new international trade agreements.

International trade agreements usually lead to an increase in the PPT, because exportations and importations are heavily affected by the international trade. Less taxes, open market and open exchange of people are fundamental steps in the making of a productive nation with an high PPC, as it possible to see with examples all over the world.