Which laboratory activity involves a chemical change? leaving a copper penny in vinegar until it turns green

boiling salt water for several minutes until only solid salt remains

extracting iron filings from a sand mixture using a magnet

crushing a rock with a hammer to extract mineral deposits

Iflow from a warmer object to a cooler object until both objects are the same temperature what am i?

Agas initially at p1 = 1 bar and occupying a volume of 0.5 liter is compressed within a piston–cylinder assembly to a final pressure p2 = 4 bar. (a) if the relationship between pressure and volume during the compression is pv = constant, determine the volume, in liters, at a pressure of 3 bar. (b) repeat for a linear pressure–volume relationship between the same end states. reference

Física: un futbolista patea hacia el arco con una velocidad de 15m/ah, calcular: a)el alcance para un ángulo de tiro de 25º, b) el tiempo que el balón permanece en el aire.