Are These Numbers in Standard Form?

Question 1:

0.463× 10 6
No

Question 2:

63.1× 10 5
No

Question 3:

2.65× 10 4
Yes

Question 4:

1.14× 10 3
Yes

Question 5:

7.9× 10 3
Yes

Question 6:

5.7× 10 5
Yes