The minimum requirements for Drupal is listed on their official page here:
https://www.drupal.org/docs/7/system-requirements/php-requirements#php_required
The table below was taken from their website as of 22 June 2022 and lists all the supported and recommended version of PHP for Drupal 7.
| PHP version | Supported by Drupal | Recommended for Drupal 7? |
|---|---|---|
| 5.3 / 5.4 / 5.5 | Yes | No |
| 5.6 | Yes | No |
| 7.0 | Yes | No |
| 7.1 | Yes | No |
| 7.2 | Yes | No |
| 7.3 | Yes | Yes |
| 7.4 | Yes, as of Drupal 7.71 | Yes |
| 8.0 | Yes, as of Drupal 7.79 | See official Drupal link |
| 8.1 | No; see official Drupal link |