Given the incomplete equation for the combustion of ethane:
2c2h6 + 7o2==> 4co2 + 6
what is the formula of the missing product?
(1) ch3oh (3) h2o
(2) hcooh (4) h2o2

Answer : The correct option is, (4)

Explanation :

Combustion reaction : It is a reaction in which a hydrocarbon react with the oxygen gas to produces carbon dioxide as water as a products.

The given incomplete equation are :

In this equation, we see that a hydrocarbon and oxygen gas are present on reactant side and carbon dioxide are present on product side but water molecules are missing on the product side. So, we are adding water on missing side.

The given complete equation will be :

Therefore, the formula missing on product is,  

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.