How many grams of oxygen are required to burn 3.01 x 10^23 propane molecules?

How does kepler second law of planetary motion overthrow one of the basic beliefs of classical astronomy

Pl what kind of reaction is this? nahco3 + h2o → co2 + naoh + h2o -composition -decomposition -single replacement -double replacement im leaning more toward single replacement. if im wrong can you explain whyy?

When does phenolphthalein turn pink? in the presence of a base in the presence of an acid when it is in a neutral solution when it is reacting with a metal