Which chemical reaction is correctly balanced? * a. CH4 +2O2 → CO2 +2H2O
b. 2CH4 +2O2 → CO2 +2H2O
c. CH4 +O2 → CO2 +H2O
d. None of the above

The answer is a. CH4 + 2O2 --- CO2 + 2H2O

Explanation:

A balanced chemical reaction must have the same number of each type of atom on both sides according to the law of conservation of mass:

1 carbon 4 hydrogen + 4 oxygen 1 carbon 2 oxygen + 4 hydrogen

2 oxygen  =

1 carbon 4 hydrogen 4 oxygen 1 carbon 4 hydrogen 4 oxygen

Since each type of atom has the same amount on both sides, the chemical formula is balanced.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.