Final answer:
Without the chemical formula of the unknown compound, it's impossible to give the grams of oxygen in the 100.0 g sample. Significant figures represent the precision of measurements in a scientific context.
Step-by-step explanation:
To determine how many grams of oxygen (O) are in a 100.0 g sample of an unknown compound, we first need to know the chemical formula of the compound to understand the ratio of oxygen in it to the rest of the elements. However, since this crucial information is missing in the question, we cannot provide a numerical answer. Significant figures are important when reporting measurements in science to indicate the precision of the measurement. For example, the number 100.0 g has four significant figures, indicating that the tenths place is measured and estimated precisely. When performing calculations, the result should match the least number of significant figures from the measured values. In scientific notation, zeros are included only if they are significant, helping to clarify any ambiguity with trailing zeros.