Which two gases in the atmosphere are essential to life on Earth? *

Nitrogen and Helium

Oxygen and Carbon Dioxide

Neon and Argon

Hydrogen and Helium

How many grams of nitrogen gas are needed to produce 34 g of ammonia

What determines the pitch of a sound wave

0.05 kg bullet is fired to the north from a 4.0 kg rifle that is initially at rest. The bullet leaves the rifle with a momentum of 20 Ns. Determine the total momentum of the bullet-and-rifle before the bullet is fired?

The moon's gravity is about half as strong as Earth's gravity. True False

6) What force should be applied to compress a spring by 0.19 m if its spring constant is k = 140 N/m?

Comparing and contrasting ionic and covalent bonds?

Elevation above sea level is called

The train traveled 500 kilometers north to Odessa in 2 hours. What's the train's speed? What is the velocity?

Are microwaves and radio waves faster or slower than other types of electromagnetic energy?

If you dive under-water, you notice an uncomfortable pressure on your eardrums due to the increased pressure. The human eardrum has an area of about 70 mm2 (7*10-5m2), and it can sustain a force of about 7 N without rupturing.