CH4 + __O2 → CO2 + ___H2O

balance this equation

CH4+2O2→CO2+2H2O

Explanation:

Start with the least common atoms and leave things like H and O to the end.

You need to have the same number of methane reactants as carbon dioxide products because there is one carbon in each. I’ll set them both to 1 for now. O see two things with oxygen on the product side so we will have to juggle numbers a bit to figure out those. There is only H in the water so we’ll go there next. One CH4 gives 2 water molecules so we have that done now. At last we can tackle the O atoms. In two waters there are 2 and in the CO2 there are two more so a total of 4 O atoms in the products so we need two O2 molecules in the reactant side.

Hope this is useful.

b. atoms in metallic solids are not arranged in a regular pattern

explanation:

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.