How is the production of mercury from burning coal an environmental hazard?
a.
High concentrations of mercury in the air leads to global warming.
b.
Mercury in water systems is transformed through biological processes into a substance that is toxic to animals.
c.
Mercury combines with other coal emissions in the air to produce ozone.
d.
All of the above

Which of these statements best describes the st. lawrence seaway? the st. lawrence seaway connects the st. lawrence river with the arctic ocean. the st. lawrence seaway provides an important trading route between the u.s. and mexico. the st. lawrence seaway provides an important trading route for the u.s, but has little value for canada. the st. lawrence seaway connects the great lakes, the st. lawrence river, and the atlantic ocean.

Up to what percentage of the world's flora consisted of cycads during the triassic period? 100% 75% 50% 20%

The polio virus can cause skeletal muscle paralysis by destroying neuron cell bodies. what area of the spinal cord is destroyed