Question

we want to find out how many grams of al are needed to react with 16 g o₂. 4al + 3o₂ → 2al₂o₃ what is the unknown in the problem? g al 16 g o₂ mol o₂

Explanation:

The problem states we want to find the grams of Al needed to react with 16 g of O₂. The unknown is the quantity we are trying to find, which is the mass of Al (in grams). The 16 g O₂ is the given mass (known), and mol O₂ would be an intermediate calculation, not the unknown we're ultimately seeking. So the unknown is g Al.

Answer:

A. g Al