how many variables are you allowed to change a purpose in a experiment

The 54.9-g sample of the compound X2O7 contains 33.6 g of oxygen atoms. What is the molar mass of element X?

When a substance goes directly from a solid state to a gaseous state?

The solution remaining from Part A, which contains 0.0100 M Ni2 and Fe2 ions, is still saturated with H2S gas, producing a concentration of 0.100 M. A buffer is added to this solution to produce a pH of 1.51.

When a bond forms between two atoms A. protons are lost. B. neutrons are lost. C. energy is released. D. energy is absorbed.

Which of the following is true about an atom of lithium and an atom of helium

Which statement correctly compares the number of chromosomes in a body cell to that in a sex cell of humans? A. A body cell has 21 chromosomes; a sex cell has 23 B. A body cell has 21 chromosomes; a sex cell has two C.

Halocarbons contain carbon, hydrogen, and atoms from which set of elements? 1. lithium, sodium, and potassium 2. nitrogen, oxygen, phosphorus, and sulfur 3. nitrogen, oxygen, and fluorine 4. fluorine, chlorine, bromine, and iodine

List at least 3 factors that can influence a body's temperature after death.

How many grams of water form when 1.24 l of gas h2 at stp completely reacts with o2?

According to the following reaction, how many grams of hydrogen peroxide ( H 2 O 2 ) are necessary to form 0.182 moles oxygen gas? hydrogen peroxide ( H 2 O 2 ) (aq) → water (l) + oxygen (g)