Question

comets are objects with three distinct parts: a nucleus, a coma, and a tail. the nucleus, or core, is made of ice, dust, and sometimes rock. most nuclei are irregular in shape and are between 100 meters and 100 kilometers in diameter. the coma is a cloud of gas that surrounds the nucleus. the tail is a long trail of gas and dust particles that extends away from the nucleus. the comas and tails of comets form when ice and dust vaporize as comets approach the sun.
comets orbit stars along oval - shaped paths. many comets in the solar system are located within the kuiper belt, a region of space beyond neptunes orbit. but many more comets may be located within the oort cloud, a region of space at the edge of the solar system. if disturbed by gravity, some comets in the kuiper belt or oort cloud can travel toward the sun into the inner solar system.
select the true statements about comets in the solar system.

• the nucleus of a typical comet is less than 100 kilometers in diameter.
• comets have a solid nucleus, a gaseous coma, and a long tail.
• comets are typically composed of metal, and contain little dust or ice.
• most comets are located well beyond the orbit of neptune.

Explanation:

1. For "The nucleus of a typical comet is less than 100 kilometers in diameter": The text says nuclei are between 100 meters and 100 kilometers, so less than 100 km is true.
2. For "Comets have a solid nucleus, a gaseous coma, and a long tail": Nucleus is ice/dust/rock (solid), coma is gas cloud, tail is gas/dust trail, so this is true.
3. For "Comets are typically composed of metal, and contain little dust or ice": The text says nucleus is ice, dust, sometimes rock – not metal and little dust/ice, so this is false.
4. For "Most comets are located well beyond the orbit of Neptune": Many are in Kuiper belt (beyond Neptune) and more in Oort cloud (edge of solar system), so this is true.

Answer:

• The nucleus of a typical comet is less than 100 kilometers in diameter.
• Comets have a solid nucleus, a gaseous coma, and a long tail.
• Most comets are located well beyond the orbit of Neptune.