I took plan b one step 24 hours after a condom broke during ovulation could i still become pregnant?

Yes: Plan b works very well when taken the day after sex. However, very well is not perfect (and nothing in this world is perfect), so there is a small chance of pregnancy. Plan b can alter one's menstrual bleeding for 1-2 cycles, so a late period doesn't necessarily mean a pregnancy. One can consider a home pregnancy test if the next period is more than a week late.

Maybe: Plan b is usually successful in avoiding an unwanted pregnancy, but no birth control method is 100% unless it is abstinence. The timing in the cycle is critical, however. As long as you were not ovulating at the time the condom broke, you are probably safe.