Question

low input impedance and low output impedance
high input impedance and high output impedance
low input impedance and high output impedance
the output characteristics of a bjt in ce mode show:
an active region where $i_c\approx\beta i_b$
different curves for different base currents $i_b$
a saturation region where $i_c$ is nearly constant despite $v_{ce}$
relationship between collector current $i_c$ and collector - emitter voltage $v_{ce}$
ing represents forward bias in a diode
no current flows regardless of voltage
large current flows after exceeding the threshold voltage
anode is positive with respect to cathode
diode behaves as an ideal short circuit without threshold voltage

Explanation:

1. For the first - part about impedance: A BJT in CE mode has low input impedance and high output impedance. This is a fundamental characteristic of the common - emitter configuration.
2. For the output characteristics of a BJT in CE mode:

• In the active region, $I_C\approx\beta I_B$.
• The output characteristics show different curves for different base currents $I_B$.
• In the saturation region, $I_C$ is nearly constant despite changes in $V_{CE}$. And the output characteristics represent the relationship between collector current $I_C$ and collector - emitter voltage $V_{CE}$.

1. For forward bias in a diode: When a diode is forward - biased, the anode is positive with respect to the cathode, and a large current flows after exceeding the threshold voltage.

Answer:

1. Low input impedance and high output impedance
2. An active region where $I_C\approx\beta I_B$, Different curves for different base currents $I_B$, A saturation region where $I_C$ is nearly constant despite $V_{CE}$, Relationship between collector current $I_C$ and collector - emitter voltage $V_{CE}$
3. Large current flows after exceeding the threshold voltage, Anode is positive with respect to cathode