The gold metal is heated, pounded and shaped until it forms a wedding ring. Chemical change or physical change?

Match the mixture with the substance// i really need on this guys (it’s a pic btw)

Given the following at 25c calculate delta hf for hcn (g) at 25c. 2nh3 (g) +3o2 (g) + 2ch4 (g) > 2hcn (g) + 6h2o (g) delta h rxn= -870.8 kj. delta hf=-80.3 kj/mol for nh3 (g), -74.6 kj/mol for ch4, and -241.8 kj/mol for h2o (g)

In the experiment you asked to react hydrochloric acid and with sodium hydroxide. when measuring the volume of the reactants, which instrument would give the greatest precision.