Explain why the rusting of an iron bar decreases the strength of the car?

What does a numerical subscript following an element in a chemical formula mean?

Question 17 hydrogen is manufactured on an industrial scale by this sequence of reactions: +ch4gh2og ⇌ +cog3h2g k1 +cogh2og ⇌ +co2gh2g k2 the net reaction is: +ch4g2h2og ⇌ +co2g4h2g k write an equation that gives the overall equilibrium constant k in terms of the equilibrium constants k1 and k2. if you need to include any physical constants, be sure you use their standard symbols, which you'll find in the aleks calculator.

When is the oxidation state of a metal indicated in the name of a compound?