A compound containing only carbon, hydrogen, and oxygen is subjected to elemental analysis.  Upon complete combustion, a 0.7916-g sample of the compound produced 1.581 g of CO2 and 0.6474 g of H2O.  What is the empirical formula of a compound?

What is true of natural selection? A) Natural selection is a random process. B) Natural selection creates beneficial mutations. C) The only way to eliminate harmful mutations is through natural selection. D) Mutations occur at random; natural selection can preserve and distribute beneficial mutations. E) Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations.

Matter is everything that has [1] and occupy [2]. 

What coefficient has to be placed in front of H2O to correctly balance following equation? Remember that entire equation has to be balanced. B2O3(s) + HF(l) → BF3(g) + H2O(l)

What is the mass in grams of one molecule of propene, C3H6?

Which of the following is the lowest temperature? TK = TC + 273 TF = (1.8 x TC) + 32 TC = (TF – 32) / 1.8

A 2.34 g sample of an element contains 2.71×1022 atoms. What is the element symbol?

Iodine pentafluoride reacts slowly with glass and violently with water. Determine its molecular mass.

Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain and waterproofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.

If a car makes 25.0 miles/gal, how many liters of gasoline are needed for a 322 km trip?   (1 mile = 1.609 km, 1 gallon = 3.79 L)