What is the correct order of events in this chain reaction (Rube Goldberg) starting with lighting a candle and ending with a TV turning on?

What you are really ordering here

Each sentence describes a cause-and-effect link. To put them in order, start with the action you can do (lighting the candle), then follow what that action directly causes, step by step, until you reach the final outcome (TV turns on).

Follow the energy transfer from one step to the next

• A candle can only affect something close to it by heat, so the next event must involve the candle burning something.
• Once the ball is released, gravity makes it roll down a ramp, so the rolling ball comes next.
• Hitting an electrical switch explains how a fan turns on.
• A running fan can push lightweight objects like books.
• Falling books can knock over a container and mix vinegar with baking soda.
• The chemical reaction produces motion (bubbling pressure), which can push or move a ruler.
• A moving ruler can let a marble fall, and the falling marble can press a remote button.

Completed sequence (with your step numbers)

1. Light the match to start the candle.
2. The candle burns the string into two pieces, releasing the ball that was being held in place.
3. The ball rolls down the ramp and hits the electrical switch turning on the fan.
4. The fan blows air, pushing the books over like dominoes.
5. The books knock a container that spills vinegar into a beaker of baking soda, which creates a chemical reaction bubbling out of the container.
6. The reaction moves a ruler holding a marble, causing the marble to fall off the ruler and hit the power button a TV remote control.
7. The remote turns on the TV.