Question: multichoices 1 a giant molecular cloud has a mean particle...

Multi-Choices

1. A giant molecular cloud has a mean particle density of 100 cm−3 . What is its mean mass density?

(a) 1.7 × 10−25 kg m−3

(b) 1.7 × 10−22 kg m−3

(c) 1.7 × 10−19 kg m−3

(d) 1.7 × 10−25 g m−3

(e) 1.7 × 10−22 g cm−3

2. What is the expected free-fall time for the cloud in the previous question?

(a) 3000 yr

(b) 30 000 yr

(c) 300 000 yr

(d) 3 000 000 yr

(e) 30 000 000 yr