Use the periodic table to compare the sizes of ionic radii with the corresponding atomic radii or other ionic radii. Choose from smaller and larger in the blanks below:
A sodium cation is
than a sodium atom.
A phosphorus anion is
than a phosphorus atom.
A magnesium ion is
than a sodium ion.
A chlorine ion is
than a phosphorus ion.
A potassium ion is
than a sodium ion.

your answer would be a. 12.5 kg

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.

answer; the numbers of valence electrons in the acetic acid molecule (ch3co2h) is 24;

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".