How do you show more than 1 of the same polyatomic ion when writing a chemical formula?

What are the resulting coefficients when you balance the chemical equation for the combustion of ethane, c2h6? in this reaction, ethane is burned in the presence of oxygen (o2) to form carbon dioxide (co2) and water (h2o). (g)+(g)→(g)+(g)

What does x represent in the formula for the compound xcl4?

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.