Question: Q: Different isotopes of an element have different mass numbers because they have different numbers of what? Read this paragraph and choose the correct option from the provided answers: An atom's mass number is its mass in atomic mass units (amu), which is about equal to the total number of protons and neutrons in the atom. Different isotopes of an element have different mass numbers because they have different numbers of neutrons. Choices: - protons - electrons - nuclei - neutrons A:
Answer: neutrons

Question: Q: Many species secrete a hard external skeleton of what? Read this paragraph and choose the correct option from the provided answers: Choices: - sodium bicarbonate - hydrogen carbonate - carbon dioxide - calcium carbonate A:
Answer: calcium carbonate

Question: Q: What is the main reason for weather change? Read this paragraph and choose the correct option from the provided answers: Weather is always changing. One day might be cold and cloudy. The next day might be warm and sunny. Even on the same day, the weather can change a lot. A beautiful morning might be followed by a stormy afternoon. Why does weather change? The main reason is moving air masses. Choices: - climate change - moving energy masses - seasons - moving air masses A:
Answer:
moving air masses