Q-factor of a circuit is defined as the ratio of energy stored in the circuit to the energy dissipated per cycle. It is also known as the quality factor or the figure of merit of the circuit. A high Q-factor indicates that the circuit is highly selective in terms of the frequency it can resonate at.

Impedance of the Circuit is High
When the Q-factor of the circuit is high, it means that the energy stored in the circuit is larger than the energy dissipated per cycle. This implies that the circuit has a low loss and high efficiency. In other words, the circuit is able to store energy for a longer time period without losing it to the environment. This results in a high impedance of the circuit. It means that the circuit can handle a large amount of power without dissipating it as heat.

Bandwidth is Large
The bandwidth of a circuit is defined as the range of frequencies within which the circuit can operate efficiently. A high Q-factor indicates that the circuit has a narrow bandwidth. This is because the circuit is highly selective and can only resonate at a specific frequency. However, if the circuit is designed to have a high Q-factor and a large bandwidth, then the bandwidth will be larger than that of a low Q-factor circuit.

Power Factor of the Circuit is not High
The power factor of a circuit is defined as the ratio of the real power to the apparent power. A high power factor indicates that the circuit is efficient in converting the input power to useful output power. However, the Q-factor of the circuit is not directly related to the power factor. Therefore, a high Q-factor does not necessarily mean a high power factor.

Conclusion
In conclusion, when the Q-factor of a circuit is high, the impedance of the circuit is high, and the bandwidth is narrow. However, a high Q-factor does not necessarily mean a high power factor.