End of chapter exercises

Give one word/term for each of the following descriptions:

Read the following extract and answer the questions that follow.

More profits, more poisons

Since the last three decades gold miners have made use of cyanidation to recover gold from the ore. Over \(\text{99}\%\) of gold from ore can be extracted in this way. It allows miners to obtain gold flakes – too small for the eye to see. Gold can also be extracted from the waste of old operations which sometimes left as much as a third of the gold behind.

The left-over cyanide can be re-used, but is more often stored in a pond behind a dam or even dumped directly into a local river. A teaspoonful of two-percent solution of cyanide can kill a human adult.

Mining companies insist that cyanide breaks down when exposed to sunlight and oxygen which render it harmless. They also point to scientific studies that show that cyanide swallowed by fish will not 'bio-accumulate', which means it does not pose a risk to anyone who eats the fish. In practise, cyanide solution that seeps into the ground will not break down because of the absence of sunlight. If the cyanide solution is very acidic, it could turn into cyanide gas which is toxic to fish. On the other hand, if the solution is alkaline, the cyanide does not break down.

There are no reported cases of human death from cyanide spills. If you don't see corpses, everything is okay.