Why Do Many H II Regions Glow with a Prominent

question 268

Multiple Choice

Why do many H II regions glow with a prominent red color?

• A) Ionized hydrogen, like neutral hydrogen, has the H_α line as one of its electron transitions.
• B) Ionized hydrogen does not emit a red line, but it has a yellow line and a magenta line, and the combination of these produces the sensation of red.
• C) Ionized hydrogen cannot be detected directly, so CO is used as a tracer, and CO produces a red line.
• D) Neutral hydrogen atoms are formed temporarily in the plasma of an H II region, and they emit the red H_α line.

---

Definitions:

Discount on Bonds Payable

The discrepancy between a bond's nominal value and its market price when the bond is sold below its nominal value.

Journal Entry

A record of a financial transaction in an accounting system, consisting of debits and credits to maintain the double-entry accounting.

Discount on Bonds Payable

The gap between the nominal value of a bond and the price it is sold at when this price is lower than the bond's nominal value.

Redeems

The act of repaying or buying back something, such as a company repurchasing its own shares or a bond issuer paying back the principal at maturity.