Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Solutes change the physical properties of solvents. They lower the freezing point and raise the boiling point of solvents. Answer: solutes

Answer: What change the physical properties of solvents?

Question: Passage: Mollusks reproduce sexually. Most species have separate male and female sexes. Gametes are released into the mantle cavity. Fertilization may be internal or external, depending on the species. Fertilized eggs develop into larvae. There may be one or more larval stages. Each one is different from the adult stage. Mollusks have a unique larval form called a trochophore . It is a tiny organism with cilia for swimming. Answer: trochophore

Answer: What is the unique larval form of mollusks called?

Question: Passage: Reptiles have a circulatory system with a heart that pumps blood. Reptiles also have a centralized nervous system with a brain. Their brain is relatively small, but the parts of the brain that control the senses and learning are larger than in amphibians. Reptiles have good senses of sight and smell. They use their tongue to smell scents. That's what the blue-tongued lizard in Figure below is doing. Some reptiles also have a heat-sensing organ that helps them locate the warm bodies of prey animals such as birds and small mammals. Answer: tongue

Answer:
Instead of using their nose, reptiles can use what organ to smell scents?