Question
A sample of $$Al{F_3}$$ contains $$3.0 \times {10^{24}}{F^ - }\,ions.$$ The number of formula unit of this sample are
A.
$$9 \times {10^{24}}$$
B.
$$3 \times {10^{24}}$$
C.
$$0.75 \times {10^{24}}$$
D.
$$1.0 \times {10^{24}}$$
Answer :
$$1.0 \times {10^{24}}$$
Solution :
An, $$Al{F_3}$$ the number of $$F$$ is 3 for one $$Al{F_3}$$ molecule $$3{F^ - } \equiv 1$$ formula unit of $$Al{F_3}$$
$$3.0 \times {10^{24}}{F^ - } \equiv \frac{1}{3} \times 3.0 \times {10^{24}}Al{F_3}\,units$$