1. The most abundant element in the universe is __________.

Hydrogen

A. Oxygen

B. Hydrogen

C. Carbon Dioxide
D. Silicon

2. The most abundant element in the Earth's crust is __________.

A. Oxygen

B. Hydrogen
C. Carbon Dioxide
D. Silicon

3. Each day human body breathe in __________ liters of air.

A. 5,000 to 10,000
B. 10,000 to 15,000

C. 15,000 to 20,000

D. 20,000 to 25,000