The table below shows the salmon population, in thousands of pounds, in Columbia River, from 1870 to 1950. Year Salmon population (in thousands of pounds) 1870 10,200 1890 20,000 1915 20,500 1931 30,000 1950 10,000 Based on the table, which of these is most likely the period during which a series of large hydropower units were built on the Columbia River? (3 points)

A student observes a star from two positions of Earth in its orbit, in summer and winter, and measures the change in the position of the star. Which of these can be best calculated by this method? (3 points)

A pond is located beside an open mine. Mercury from the mine contaminates the river water. This is an example of (3 points)

Which of these waves travel the fastest? (3 points)

Which statement best explains why the Big Bang Theory is the leading scientific explanation of the development of the universe over time? (3 points)

Hydroelectric power plants can generate huge amounts of electricity. Which of these statements best describes the impact of a hydroelectric power plant on the environment? (3 points)

The picture below shows a land surface in a location in Florida. Which of these most likely caused the cavities in the land surface? (3 points)

Which of these surface features are formed because of the heating of groundwater? (3 points)

The picture below shows a science model. The model most likely represents a (3 points)

Scientists believe that the Earth’s orbit gradually changes from being elliptical to being nearly circular and then back to elliptical in a period of about 100,000 years. This causes global climatic change. The more elliptical the Earth’s orbit, the greater the difference in (3 points)