Questions

Bioaccumulation is defined as the increase in concentration of a substance(s) in an organism or a part of that organism.

The affected organism has a higher concentration of the substance than the concentration in the organism's surrounding environment.

For the second statement: Microorganisms eat pesticide infected things. Invertebrates eat hundreds of the microorganisms and plants infected with the pesticides, accumulating a pretty large amount of the toxin in them.

The invertebrates are generally then eaten by larger invertebrates or amphibians, which ingest hundreds of similar organisms, accumulating an even higher concentration of toxins in their bodies. Then the fish eat hundreds of these organisms, accumulating the highest concentration of toxins in themselves.

The case where there is 6 months day, and 6 months night could only happen on poles because The Earth is tilted on its axis.

The pole which is away (opposite direction of sun) from the Sun remains in complete darkness till it comes in front of the sun.

So we conclude that, countries at the poles have 6 months day, and 6 months night.

So countries close to these region have such cases like, Alaska, Antarctica, Norway etc.

Norway, the northernmost inhabited region of Europe, there is no sunset from approximately 19 April to 23 August. The extreme sites are the poles, where the sun can be continuously visible for half the year. The North Pole has midnight sun for 6 months from late March to late September.

The chemical name of the compound 

Cu2CO3 isCopper (i) carbonate and is also called as cuprous carbonate.