Hi, let us know what your list of countries is!
In the meantime, I will give you some information, hopefully it will help:
In constitutional monarchies the Head of state, the monarch is only ceremonial. this includes for example all the European monarchies, all the countries in which the British Monarch is the head of state and Japan.
Also, in parliamentary systems the head of state, the president is also ceremonial. This includes The central European democracies (Germany, Austria) and India and Pakistan)
The correct answer is - cyanobacteria.
The atmospheric oxygen came from the cyanobacteria. These were one of the earliest living organisms on Earth. The cyanobacteria was using photosynthesis in order to create its own food. The photosynthesis process requires sunlight, carbon dioxide, water, and oxygen. The oxygen is mostly released as a waste product from the process of photosynthesis, thus the cyanobacteria were literally releasing oxygen that was ending up into the atmosphere. As more and more cyanobacteria there were across the planet, more and more oxygen they were releasing into the atmosphere, slowly changing the composition of the atmosphere, and setting the basis of it as we know it now.
Radiometric dating is dating a rock or mineral by measuring the proportions of an original radioactive material and its decay products. We need to know the rate at which radioactive decay occurs and <span>how much radioactive decay has occurred. Hope this answers the question. Have a nice day.</span>
