Calculate the mass in grams for 1.56 x 10^24 atoms of Ne. Express your answer to three significant figures and include the appropriate units. Show work.

You have two distinct gaseous compounds made from element X and element Y. The mass percents are as follows: Compound I: 30.43% X, 69.57% Y Compound II: 63.64% X, 36.36% Y In their natural standard states, element X and element Y exist as gases. (Monatomic? Diatomic? Triatomic? That is for you to determine.) When you react gas X with gas Y to make the products, you get the following data (all at the same pressure and temperature): 1. volume gas X + 2 volumes gas Y2 volumes compound I 2. volumes gas X + 1 volume gas Y2 volumes compound II Assume the simplest possible formulas for reactants and products in the chemical equations above. Then, determine the relative atomic masses of element X and element Y.

Cyclopropane mixed in the proper ratio with oxygen can be used as an anesthetic. At 755 mm Hg and 25C, it has a density of 1.71 g/L. (a) What is the molar mass of cyclopropane? (b) Cyclopropane is made up of 85.7% C and 14.3% H. What is the molecular formula of cyclopropane?

A sample of cocaine, C17H21O4N, is diluted with sugar, C12H22O11. When a 1.00-mg sample of this mixture is burned, 1.00 mL of carbon dioxide (d=1.80g/L) is formed. What is the percentage of cocaine in this mixture?