سؤال قراءة ستيب محلول — المفردات في السياق (تدريب 5461)

(1) A chemical formula, in combination with the molar masses of its main elements, indicates the relative quantities of each element in a compound, which is extremely useful information. For example, about 30 years ago, scientists began to suspect that synthetic compounds known as chlorofluorocarbons (or CFCs) were destroying the ozone in Earth’s upper atmosphere. (2) Upper atmospheric ozone is important because it shields life on Earth from the sun’s harmful ultraviolet light. CFCs are chemically inert compounds that were used primarily as refrigerants and industrial solvents. Over time, however, CFCs began to accumulate in the atmosphere. In the upper atmosphere, sunlight break bonds within CFCs, resulting in the release of chlorine atoms. The chlorine atoms then react with ozone, converting it into O2. Therefore, the harmful part of CFCs is the chlorine atoms that they carry.