The gas given off when NH4 Cl is heated with an alkali is
Answer Details
When NH4Cl is heated with an alkali such as NaOH, it undergoes a decomposition reaction to form NH3 gas, water, and a salt. The balanced chemical equation for the reaction is: NH4Cl + NaOH → NH3 + H2O + NaCl Therefore, the gas given off is NH3, which is ammonia (option D).