What is always true of a combustion reaction?

carbon dioxide will be produced

the reaction absorbs energy

oxygen gas must be one of the reactants

one reactant must contain carbon

answer: oxygen gas must be one of the reactants

explanation: combustion reaction is a reaction in which a substance burns in the presence of oxygen to give large amounts of energy.

a) carbon dioxide is produced when hydrocarbons undergo combustion reaction.

b) combustion reactions are almost always accompanied by release of energy, they are exothermic reactions.

c) combustion takes place in the presence of molecular oxygen which is present in gaseous form   thus oxygen gas must be one of the reactants

d) it is not necessary. even inorganic compounds undergo combustion.

it is important to conserve water because there is very limited amount of freshwater here on earth and if we are not smart about how we use it we will only be runnning out of our supply faster than neccessarry.

each  column  of the  table  is called a group. elements in a group share similar properties. groups are  read  from  top  to  bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o.  2. 3. 4. 5. 6. 7. 8. 9.  2. beryllium. 9.012. 4.  sodium. 22.990.  11. 3.  magnesium. 24.305.  12.  potassium. 39.098.  19. 4.  calcium. 40.078.  20. i guess  i