Need with algebra

1. simplify. 5–1(3–2) (1 point)
a)45
b)1/45
c)15^–3
d)15^2 

2. simplify. mn^-4/p^0q^-2 (1 point)
a)mq^2/n^4
b)mp/n^4
c)mn^4q^2p^0
d)q^2/mn^4 

3. write in scientific notation. 0.0042 (1 point)
a)42 × 10^2
b)4.2 × 10^4
c)4.2 × 10^3 
d).42 × 10^4

4. write in standard notation. 6.12 × 10^3 (1 point)
a)6,120 
b)612
c)61,200
d)61.2

5. simplify. write in scientific notation. 0.5(8 × 10^5) (1 point)
a)8 × 5^5
b)4 × 5^5
c)8 × 10^5
d)4 × 10^5 

6. simplify. write in scientific notation. (9 × 10^3)^2 (1 point)
a)8.1 × 10^5
b)81 × 10^4
c)81 × 10^3
d)8.1 × 10^6 

7. evaluate 1/2a^4b^2 for a = –2 and b = 4. (1 point)
a)2 
b)1/2
c)3
d)4

8. is the following statement always, never, or sometimes true?
a number raised to a negative exponent is negative. (1 point)
a)always
b)never
c)sometimes 

9. simplify (4xy^2)^3(xy)^5 (1 point)
a)64x^8y^11
b)64x^15y^30
c)12x^2y^11
d)12x^8y^11 

10. simplify (2t^3)^3(0.4r)^2 (1 point)
a)3.2r^2
b)1.28r^2/t^-6 
c)1.28r^2/t^9
d)0.8r^2/t^-6