Calculate the mass, in kg, of sample.  7.55x10^26 cadmium atoms

A substance X2Z has the composition (by mass) of 40.0% X and 60.0% Z. What is the composition (by mass) of the compound XZ2?

1. Which of the following hydrocarbons has the highest mass percentage of carbon? methane, CH4 ethane, C2H6 propane, C3H8 butane, C4H10

A sample of an iron alloy contains 92.1 g Fe. 2.59 g C. and Cr. Calculate the percent by mass of each component present in the alloy sample.

opical hydrocortisone is often used to treat a variety of skin conditions, such as insect bites, eczema, and rashes. Each molecule of hydrocortisone contains 21 atoms of carbon (plus other atoms). The mass percentage of carbon in hydrocortisone is 69.5 8%. What is the molar mass of hydrocortisone?

Chalky, white crystals in mineral collections are often labeled borax, which has the molecular formula Na2B4O7 10H2O, when actually they are partially dehydrated samples with the molecular formula Na2B4O7 5H2O, which is more stable under the storage conditions. Real crystals of borax are colorless and transparent. (a) Calculate the percent mass that the mineral has lost when it partially dehydrates. (b) Is the percent boron by mass the same in both compounds?

A gas contains a mixture of NH3(g) and N2H4(g), both of which react with O2(g) to form NO2(g) and H2O(g). The gaseous mixture (with an initial mass of 61.00 g) is reacted with 10.00 moles O2, and after the reaction is complete, 4.062 moles of O2 remains. Calculate the mass percent of N2H4(g) in the original gaseous mixture.

Is there a difference between a homogeneous mixture of hydrogen and oxygen in a 2:1 mole ratio and a sample of water vapor? Explain.

Chlorine exists mainly as two isotopes, 37Cl and 33Cl. Which is more abundant? How do you know?

The compound As2I4 is synthesized by reaction of arsenic metal with arsenic triiodide. If a solid cubic block of arsenic (d = 5.72 g/cm3) that is 3.00 cm on edge is allowed to react with 1.01 1024 molecules of arsenic triiodide, what mass of As2I4 can be prepared? If the percent yield of As2I4 was 75.6%, what mass of As2I4 was actually isolated?