Which type of reaction is 2c2h6 + 7o2 → 4co2 + 6h2o? a. decomposition reaction b. synthesis reaction c. combustion reaction d. double-replacement reaction

C) Combustion reaction.

Explanation: a combustion reaction is an exothermic reaction in which something reacts with oxygen. The combustion of organic compounds usually takes the form: organic compound + oxygen => water + carbon dioxide. As we can see the given reaction is an organic compound (C2H6) plus oxygen (O2) and the products are carbon dioxide (CO2) and water (H2O), so it is a combustion reaction.

a

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.