Determine the number of atoms of hydrogen in  0.2355 moles of caffeine, C8H10N4O2.  (If you wish, you can show math work for possible partial credit.)

Silver ions can be precipitated from aqueous solutions by the addition of aqueous carbonate:             2  AgNO3 (aq) + Na2CO3 (aq)  →  Ag2CO3(s) + 2 NaNO3 (aq)   Silver carbonate is virtually insoluble in water so that the reaction appears to go to completion. What volume of a 3.550 M Na2CO3 must be added to a solution containing 0.700 mol of AgNO3 to completely precipitate the silver? (If you wish, show your work for possible partial credit.)

Identify the spectator ions in the following molecular equation. Na2CO3(aq) + Sr(NO3)2(aq)  →  2NaNO3(aq) + SrCO3(s)   

Aqueous solutions of magnesium chloride and sodium hydroxide react to produce solid magnesium hydroxide and aqueous sodium chloride. What is the stoichiometric coefficient for sodium chloride when the chemical equation is balanced using the lowest whole-number stoichiometric coefficients?

Brad often watches advertisements for acne removal creams. When he listens to claims that the product makes the users’ skin clearer in a few hours, he wonders, “No one’s skin can become clear within hours. The product will not work.” Brad’s thoughts are examples of _____.

Which of the following statements best defines black markets?

Atoms of the same element with different mass numbers are called

Express the fraction 1/23 as a decimal to 4 significant figures.

Which is the correct formula for lead(IV) chloride?

There are two stable isotopes of chlorine: chlorine-35, with a mass of 34.968853 amu; and chlorine-37, with a mass of 36.965903. Given that the average atomic mass of a chlorine atom is 35.45 amu, which of the following statements is true?