Answer: It is an exothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in it.
Explanation:
Endothermic reaction : It is a type of chemical reaction where the energy is absorbed from the surrounding. In the endothermic reaction, the reactant are less than the energy of product. In endothermic reaction, the change in enthalpy is, positive
Exothermic reaction : It is a type of chemical reaction where the energy is released into the surrounding. In the exothermic reaction, the energy of reactant are more than the energy of product. In exothermic reaction, the change in enthalpy is, negative.
Thus as energy is absorbed by water, which has been released by NaOH, the process is exothermic.
The formula unit of compounds formed depends on the valency of the combining ions.
The formula unit is the smallest unit of an ionic substance that gives us a picture of the ratio in which ions are combined in the ionic compound.
Usually, the formula unit is written based on the valency of the ions.
For the ions listed;
Li+ and 02- forms Li2O
Mg2+ and S2- forms MgS
A13+ and CI- forms AlCl3
Na+ and N3- forms Na3N
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Answer:
three valence electrons
Explanation:
Gallium has three electrons in the outer energy level and therefore has three valence electrons. The identification of valence electrons is vital because the chemical behavior of an element is determined primarily by the arrangement of the electrons in the valence shell.
Galileo disproved the Ptolemaic theory, sanctioned for centuries by the Church, which held the Earth to be the central and principal object in the universe, about which all celestial objects orbited.
