1. Write the exponential expression $5^3$ in expanded form. $\_\_\_$
2. Write the expression $4 \cdot 4 \cdot 4 \cdot 4 \cdot 4$ in exponential form. $\_\_\_$
3. Write the expression $y \cdot y \cdot y \cdot y \cdot y \cdot y$ in exponential form. $\_\_\_$
4. Write the expression $3 \cdot 3 \cdot 3 \cdot 3 \cdot 3 \cdot 3$ in exponential form. $\_\_\_$
5. Write the expression $x \cdot x \cdot x \cdot x \cdot x$ in exponential form. $\_\_\_$
6. Simplify the expression: $(4y)^0 = \_\_\_.$
7. Simplify and write the expression without negative exponents: $\frac{16x^{-8}}{-8x^8} = \_\_\_.$