Solution:

When comparing weights with a scale, the heavier object will be lower and the lighter object will be higher.

1. The cabbage is heavier than the eggplant. The eggplant is heavier than the chili pepper. So, the heaviest one is the cabbage! The eggplant is lighter than the cabbage and heavier than the chili pepper, so it's in the middle. The chili pepper is the lightest.
2. The tomato is heavier than the onion. The potato is heavier than the tomato. So, the potato is the heaviest one. The tomato is lighter than the potato and heavier than the onion, so it's in the middle. The onion is the lightest.
3. The pumpkin is heavier than the carrot. The carrot is heavier than the mushroom. So, the heaviest one is the pumpkin. The carrot is in the middle. The mushroom is the lightest.

Solution:

1. How many rabbits weigh as much as a dog and a pig put together? We can check each part, then add up the whole. A dog weighs as much as 2 rabbits. A pig weighs as much as 4 rabbits. Find out the whole by adding them together, 2 plus 4 equals 6. The correct answer is 6 rabbits!
2. Observe the fruits on the scale. One melon weighs as much as 3 apples, and 1 apple weighs as much as 3 oranges. How many oranges weigh as much as 1 melon? Let's solve it step by step. First replace 1 melon with 3 apples, because they are the same weight. How many oranges weigh as much as 3 apples? The correct answer is 9 oranges!