Summarize how the periodic table is organized, use the worlds period and group

The periodic table is organized into groups (columns) and periods (rows).

Explanation:

The periodic table is organized into groups (columns) and periods (rows). The first ones contain those elements that have the same valence and have similar characteristics to each other. Example: group IA have valence 1 (they require 1 electron to reach the octet). The exception to this are the noble gases located in the last group to the right of the table, which have already filled their last energy level.

Periods have elements that have the same number of orbitals and have different properties; although the masses are similar.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

a is the correct answer