Is 600 standard form

Answer 1

In USA when considering standard and expanded forms, Yes

Otherwise:

Standard form (also known as "standard index form" or "scientific notation") requires a single non-zero digit before the decimal point and a multiplier of a power of 10 which gets the decimal point back to where it was in the original number. To calculated the power of the ten count how many digits the decimal point needs to move; if it needs to move to the left make it negative.

As it does not have a multiplier of a power of 10, No.

600 = 6 × 10² in standard form.