What was first responsible for changing the formerly poisonous atmosphere to an oxygen-rich atmosphere as we have today?

Meteor impacts

Volcanic gases

Earthquakes

Photosynethic bacteria (Cyanobacteria)

An element has 76 protons, 76 electrons, and 114 neutrons. what isotope is it?

What's the mass if a nickel

What mass of NH3 can be made from 1221g of H2 and excess N2

The type of radiation which is identical to a high energy electron is known as a (n)

Which of the following is not true about the importance of the carbon cycle to living things? a. Plants use carbon dioxide to make energy. b. Carbon is the second most abundant molecule in organisms. c.

Pure aluminum metal has a density of 2.70 g/cm

A 0.250-g chunk of sodium metal is cautiously dropped into a mixture of 50.0 g of water and 50.0 g of ice, both at 08C. The reaction is 2Na (s) 1 2H2O (l) 88n 2NaOH (aq) 1 H2 (g) DH 5 2368 kJ

How many moles of N are in 0.203 g of N2O?

An atom has a charge of +1 in its nucleus. Which statement must be true in order for this atom to have no net charge? A. The one positive proton has no influence on the overall charge of the atom. B.

A chemist uses 0.25 L of 2.00 M H2SO4 to completely neutralize a 2.00 L of solution of NaOH. The balanced chemical equation of the reaction is given below. What is the concentration of NaOH that is used?