Erbium (Er) is element 68 on the periodic table. A sample contains 5.04*1023 atoms of Er. Calculate the amount of Er.

When the products of a reaction have a lower enthalpy than the reactants___? 1) the reaction is endothermic 2) the reaction is exothermic 3) the change in enthalpy is positive 4) the reactants lost internal energy

How are molecules and ionic compounds the same?

How is the amount of sunlight affect the makeup of an ecosystem

How does the precision of the absolute-age dating compare to the precision of relative-age dating?

How many grams of CO2 are in 2.1 mol of the compound?

Silver chromate is sparingly soluble in aqueous solutions. the ksp of ag2cro4 is 1.12 * 10-12 m3. what is the solubility (in mol/l) of silver chromate

What do you think 1,5-pentanedithiol C5H12S would smell like

If an atom has sp hybridization in a molecule: the maximum number of σ bonds that the atom can form is

What is an oxidizing agent?

In times of hot dry weather some cities ban the use of garden sprinklers why do you think there is such a rule