You would find most emission nebula in the 

Globular clusters

The most abundant element in the Sun is 

You would find a supermassive black hole in the

Describe one feature of the moon Titan that makes it unique among the moons of the Solar System.

The most common way of creating a black hole is 

The atmospheric gas primarily responsible for the greenhouse effect on terrestrial planets is 

The inner lining of the female uterus is the

The liver produces

Each mammary gland contains how many lobes located around the nipple