How many elements are there in the periodic table?

In which Era did the first fish appear?

A buffer is made up of 0.300 L of each of 0.500 M KH2PO4 and 0.317 M K2HPO4. Assuming that volumes are additive, (a.) calculate the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of buffer and (b.

A piece of sodium metal can be described as a pure substance and a compound. an impure substance that is reactive. an impure substance that is unreactive. a pure substance and an element.

Which statement is true about the potential energy diagram for an endothermic reaction A. the potential energy of the products is equal to the potential energy of the reactants B. it starts at a higher energy value and ends at a lower energy value C.

German scientist alfred wiener is best known for what hypothesis?

Which statements about isozymes are true? Isozymes catalyze different reactions. Isozymes have identical kinetic properties. Isozymes are present in various developmental stages. Isozymes are encoded by the same gene.

A fog over a lake. what two changes of state must occur to produce the fog? do the water molecules absorb or release energy during these changes of state? what happens to the motion of the water molecules as a result?

Limes have a [H3O+] of 1.3 x 10-2 mol/L. Their pOH is

The human body is 0.0040% iron. How many milligrams of iron does a 165 pound person contain?

Which of the following is the correct Lewis structure for ammonia (NH3) ? Note: Hydrogen and nitrogen have one and five valence electrons respectively.