Biochemistry is the study of biology and chemistry. Hydrochloric acid is the only chemical listed that does not occur naturally. Positive scientific attitudes include implementing scientific knowledge in daily life, adhering to scientific knowledge, and being concerned about environmental pollution. Making questions is not included in the scientific method concept. Given that the compound has a relative molecular mass of 144 and sulfur's relative atomic mass is 32, the relative atomic mass of X must be 28. The compound that exists as a solid at 23°C is the one with a melting point of 15°C.