D. For the first one
C. For the second one
They are electromagnetic waves because mechanical waves have to be physically created by something, while electromagnetic waves are just emitted without any effort or force.
The abiotic parts of an ecosystem are water, soil, air and dead organic matter. The correct options among all the options that are given in the question are the second, fourth, sixth and seventh options. They are basically non-living things that are present in the ecosystem. I hope it helps you.
By reducing the need for fossil fuels through the use of the ethanol biofuel.
Answer:
Over the last two centuries the dipole strength has been decreasing at a rate of about 6.3% per century. At this rate of decrease, the field would be negligible in about 1600 years. However, this strength is about average for the last 7 thousand years, and the current rate of change is not unusual.
