What does the “188” represent in Tantalum-188 A. mass number
B. atomic number
C. mass defect

mass number

Explanation:

When there is an element name followed by a dash and then a number, the number simply represents the mass number.

for example:

Oxygen- 18

18 represents the mass number of this particular isotope

i do not get it   at all

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.