The statement is true. When using the apparatus shown to find the empirical formula of magnesium oxide, it is important to lift the crucible lid occasionally to allow smoke to escape.
The statement is true.
When using the apparatus shown to find the empirical formula of magnesium oxide, it is important to lift the crucible lid occasionally to allow smoke to escape. This is because smoke is a byproduct of the chemical reaction that forms magnesium oxide, and if it is not allowed to escape, it can affect the accuracy of the measurements.
By lifting the crucible lid, the smoke is released, and the remaining mass of the crucible and the magnesium oxide can be accurately measured. This is necessary to determine the empirical formula of magnesium oxide.