Answer:
[tex]7 \times 10^{-3}[/tex]
Step-by-step explanation:
[tex]\begin{aligned}\dfrac{6.3 \times 10^{-5}}{9 \times 10^{-3}} & =\dfrac{6.3}{9} \times \dfrac{10^{-5}}{10^{-3}}\\\\& = 0.7 \times \dfrac{10^{-5}}{10^{-3}}\end{aligned}[/tex]
[tex]\textsf{Apply exponent rule} \quad \dfrac{a^b}{a^c}=a^{b-c}:[/tex]
[tex]\begin{aligned}\implies 0.7 \times \dfrac{10^{-5}}{10^{-3}} &=0.7 \times 10^{-5-(-3)}\\& = 0.7 \times 10^{-2}\end{aligned}[/tex]
[tex]\textsf{Rewrite}\:0.7\:\textsf{as}\: 7 \times 10^{-1}:[/tex]
[tex]\implies 0.7 \times 10^{-2}=7 \times 10^{-1} \times 10^{-2}[/tex]
[tex]\textsf{Apply exponent rule} \quad a^b \times a^c=a^{bc}:[/tex]
[tex]\implies 7 \times 10^{-1} \times 10^{-2}=7 \times 10^{-3}[/tex]
