<span>A method of processing coal to remove contaminants by mixing coal in a solution of potassium permanganate in a selected concentration range, rinsing the coal, mixing the coal in a solution of ammonia hydroxide in a selected concentration range to cause the solution to be brought into contact with the surfaces and pores of the coal, discharging the processed coal from the second reaction vessel, monitoring the process to detect when the concentration of aqueous ammonia in the second reaction vessel has fallen below the selected range, and feeding aqueous ammonia solution with an ammonia concentration in or above the selected range to the second reaction vessel to return the solution to within the selected range.</span>
Answer:
Explanation: The United States of America and Canada have one of the worlds oldest environmental partnerships. The various ways they're partnering to better the environment include:
1. The U.S. - Canada Air Quality Agreement.
This Agreement was signed in 1991 with the aim of working towards the reduction of air emissions which cause cause acid rain. The Agreement was later expanded in the year 2000 with the goal of reducing transboundary smog emissions under the Ozone Annex.
2. The Great Lakes Water Quality Agreement.
This Agreement was initially signed in 1972, and amended in 2012. The goal of the Agreement is to provide a mechanism that involves the effort and cooperation of both countries, that will be geared toward the protection of the Great Lakes Basin ecosystem.
Answer: 
Explanation:
The Tropic of Cancer is one of the parallels (imaginary line around the Earth parallel to the equator) located in the northern hemisphere (currently its latitude is 
).
It is called "Cancer" because a long time ago, when the summer solstice occurred in the northern hemisphere (on June 20th or 21st), the Sun was in the constellation Cancer (the crab).
Now, if we were just in the North Pole, Polaris would by exactly over our heads (
over the horizon), but as we go south and find the Tropic of Cancer parallel, Polaris altitude will be approximately at an angle of over the horizon.
Hence, the altitude of Polaris measured by an observer at the Tropic of Cancer is .
Answer: Subduction
Explanation:
Because it was in the lesson
The continent with the largest population is africa
