Which statement about the Periodic Table is correct? A Elements are arranged in order of decreasing proton number.
B Group number is the number of electron shells in atoms of the elements in the group.
C Group numbers can be used to predict the charges of ions.
D Metallic character increases left to right across a period.

answer :c

explanation :

group numbers can be used to determine the number of electrons in the outer most shell thus if the group numbers are above four then the elemnts are negative ions if less than four then posetive

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.

what is the question here. i think you messed up.