Can someone please answer these 2 questions for me ? 1. How many O elements(s) is (are) there in water?

2. How do you know the number of H and O elements in water?

There is two O elements and there is 1 H and two O elements because water is H2O

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.