Main Answer:
NH3's molar mass, 1.5 times smaller than Cl2, matches the given conditions, identifying substance a as ammonia in the mixture.
Step-by-step explanation:
The molar mass of chlorine gas (Cl2) is approximately 70.9 g/mol. Given that 65.0 g of chlorine gas is present, this corresponds to about 0.917 moles (65.0 g / 70.9 g/mol). The unknown substance a has 1.5 times as many molecules as chlorine gas, meaning it has a molar mass 1.5 times smaller than chlorine. This leads to a molar mass of approximately 47.27 g/mol (70.9 g/mol / 1.5).
Comparing this molar mass with the options provided, it matches the molar mass of ammonia (NH3). Ammonia has a molar mass of about 17.03 g/mol, which is indeed approximately 1.5 times smaller than that of chlorine gas. Therefore, the identity of substance a is NH3.
The reasoning behind this lies in the concept of molar mass and the given ratio of molecules. By determining the molar mass of chlorine gas and applying the given ratio, we can identify the unknown substance a as ammonia (NH3).