Which sample is a pure substance?

Are all molecules compounds? Explain.

Why are reactions of ionic compounds very fast?

Identify the missing information for each atom or ion. Note that the atoms and ions are not necessarily neutral. A Se ion has a mass number of 78 and a charge of - 2. Determine the number of neutrons, protons, and electrons in this ion.

Which of the following is a chemical property of water at 4 c

Technetium-99m, a "metastable" nuclide of Tc is produced by the reaction ? → 99mTc + β What is the starting nuclide? 1. 100Mo 2. 100Tc 3. 100Ru 4. 99Mo 5. 99Ru 6. 99Tc

How many atoms are in 151 g of calcium?

Which statements about the formation of the solar system are true and in a correct order? A. A black hole collapsed to form the sun; small planetary objects formed; small planetary objects collided with each other to form larger objects. B.

Which is an important step in the alternate method for balancing equations in redox reactions? a) indicating the types of bonds found in the molecules. b) determining the speed at which reactions take place.

How many moles of NH3 can be produced from 24.0 mol of H2 and excess N2

An ecosystem contains all the biotic and abiotic factors in an area. answers true or false