Agricultural chemicals:

increase food production
have caused human deaths
are sometimes difficult to destroy
all of the above

Agricultural chemicals  

b.

developed countries have tended to improve the environment, while developing countries have tended to damage it.

true. earthquakes are felt whenever there is a slip around a fault in the rocks below the earth. this reorientation of faults create sesmic waves and is known as earthquake, the severity of which is measured in richter scale. these are more prominent in hilly regions as the rocks usually form faults to balance the pressures on it.