What does it mean when something has a high ph level? low ph level ?

Why does sweden and norway have steep roofs

In wegener’s evidence for continental drift, continents were proposed to fit together, such as the east coast of south america with the west coast of europe. east coast of africa. west coast of greenland. lower west coast of africa.

This is a 2017 topographic map of puerto rico in the united states, and i'm sorry that people there have suffered such a disaster. i want to ask, what do the yellow dots and areas represent on this graph? and the blue area and the little blue circle, and the little blue sign that looks like a signal tower, what do they stand for?