In a lab, silver nitrate, AgNO3, is dissolved in water until no solid is observed in the container. Then, a solution of sodium chloride, NaCl, is added to the container. When you combine these aqueous solutions, there is no noticeable change in temperature; however, a solid precipitates and there is a slight change of color. Which statements about the lab experiment involving silver nitrate and a sodium chloride solution are true?

Formation of a solid indicates a chemical reaction occurred.

True

Explanation:

A chemical reaction is said to have occurred when a new substance(s) is (are) formed.

When we mix the sodium nitrate and sodium chloride, the following chemical reaction occurs;

2AgNO3(aq) + 2NaCl(aq) > 2AgCl(s) + 2NaNO3(aq)

The appearance of a solid shows that a chemical reaction has occurred and that NaCl really reacted chemically with AgNO3.

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.