What is the molar ratio of O2 to water

To answer this u must simply find the number of mole of each element by using the formula

Number of moles = mass / relative formula mass (Mr)

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: