Final answer:
The most frequently used barbiturates for induction are propofol, methohexital, and thiopentone/thiopenta.
Step-by-step explanation:
The most frequently used barbiturates for induction are propofol, methohexital, and thiopentone/thiopenta. These barbiturates are commonly used by anesthetists to induce a state of unconsciousness quickly and reliably. Other drugs such as benzodiazepines like midazolam may also be used in combination with barbiturates for induction purposes.