How much it has to drop and how heavy it is. Hope this is what you're looking for:)
Al is the reducing agent.That is answer B is the above answer
Al acts as a strong reducing agent. It reduces crO3 to form cr while Al is oxidized to Al2O3. Al is capable to reduce cr since Al is higher in reactivity series than cr.
apparently colorless light, for example ordinary daylight. It contains all the wavelengths of the visible spectrum at equal intensity.
B! because the hydrogen causes some nuclear reactions.