Chapter 6

1. Generally speaking, yes. It's safe to try because a higher resistance results in a lower current in the circuit (Ohm's law) and 330Ω is relatively close to the desired 200Ω resistor.
2. The higher resistance has resulted in less current to the point that there is not enough current for the circuit to operate reliably.

3. The amount of power to be dissipated by the resistor exceeds the resistor's power rating. In addition to using Ohm's law to determine a resistor value, you also need to calculate the expected power dissipation of the resistor and ensure that the resistor's power rating (in watts) exceeds your calculated value.
4. 1 (one). An input GPIO pin connected to +3.3 volts is a logical high.
5. GPIO 21 is floating. It's not pulled up to +3.3 volts by a physical resistor or via code using a function call such as pi.set_pull_up_down(21, pigpio.PUD_UP).
6. You must use a logic level converter. This could be a simple resistor-based...