Question

What are dust-sized grains made of?

1) Iron and rocky materials
2) Plastic and glass
3) Wood and paper
4) Water and air

Answer 1

Interstellar dust grains are made up of a rocky core surrounded by an icy mantle. The cores can be rich in carbon or silicates, while the mantles contain ices such as water, methane, and ammonia.

Step-by-step explanation:

A typical interstellar dust grain consists of a core of rocky material (silicates) or graphite surrounded by a mantle of ices. These dust grains can be characterized as sootlike (rich in carbon) or sandlike (containing silicon and oxygen). They are also found in meteorites and can be identified by different isotopes. The most common ices found on the grains are water, methane, and ammonia.