Simplify each expression.
1. (p^4q^2)(p^7q^5)
2. 3f^3g^0
3. (4h^5k^3)(15k^2h^3)
4. (-5a^2b)(2ab^2c)(-3b)
5. 4x(2x^2y)^0
6. (3x^4y)(2y^2)^3