Are These Numbers in Standard Form?

Question 1:

8.61× 10 3
Yes

Question 2:

0.859× 10 5
No

Question 3:

7.74× 10 5
Yes

Question 4:

96.1× 10 -6
No

Question 5:

38× 10 3
No

Question 6:

4.9× 10 -4
Yes