Which laboratory results will tell whether an unknown white solid is `NaOH` or `NH_(4)NO_(3)`?
A. `NaOH` is soluble in `H_(2)O` but `NH_(4)NO_(3)` is not
B. Aqueous `NaOH` truns litmus blue but `NH_(4)NO_(3)` does not
C. Aqueous `NaOH` reacts with copper metal but `NH_(4)NO_(3)` does not
D. `NaOH` gives a green flame test but `NH_(4)NO_(3)` is colourless in a flame
