Janice mixed an orange solution of sodium sulfide with a clear solution of hydrochloric acid. She noticed after a minute that the solution smelled something like rotten eggs. What could she reasonably infer from the odor released by the solution?
A.
Hydrochloric acid must smell like rotton eggs.
B.
A chemical reaction may have occurred.
C.
Chemical changes always produce odors.
D.
A chemical reaction must have occurred.
plz help

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.