To determine whether the statements in Task 5 are true or false, you would need to listen to the guide at the wildlife park. However, based on general knowledge, here are the likely answers:

1. Sharks are more dangerous than crocodiles. - F (False)
- Crocodiles are generally considered more dangerous to humans than sharks.

2. Crocodiles are slower than most humans on land. - F (False)
- Crocodiles can actually run faster than humans over short distances.

3. Tigers are the heaviest of the big cats. - T (True)
- Tigers are indeed the heaviest of the big cats.

4. Giraffes are the tallest land animals. - T (True)
- Giraffes are the tallest land animals.

5. Dolphins are more intelligent than gorillas. - This one is debatable and depends on the criteria used to measure intelligence. Generally, both dolphins and gorillas are considered highly intelligent animals, but it's difficult to definitively say one is more intelligent than the other without specific context.

For accurate answers, you should listen to the guide's explanations in the audio provided.