What is the half-life of a radioisotope if 25.0 grams of an original 200.-gram sample of the isotope remains unchanged after 11.46 days?

(1) 2.87 d (3) 11.46 d

(2) 3.82 d (4) 34.38 d

Using the periodic table is the elements how many valence electrons would helium have

A certain half-reaction has a standard reduction potential. an engineer proposes using this half-reaction at the anode of a galvanic cell that must provide at least of electrical power. the cell will operate under standard conditions.

What is the molar mass for chlorine gas

Moles of Zn (NO3) 2 in 161.50 g of this substance.

PbSO4 → PbSO3 + O2 Balance the equation

What is the name fro H2O

A scientist has a tomato plant with red-skinned tomatoes. It has one allele for red skin (R) and one for yellow skin (r). Which describes the phenotype of the tomato plant?

Which of the following sentence best describes a buffer? A. Buffer is A substance that resists small change in the acidity of a solution when an acid or base is added to the solution. B.

Hydrogen and oxygen bond to form water. What is the chemical formula for each of these reactants? A. H and HO B. O and HO C. H and O D, HO and O

Which molecules would most likely cause a liquid to have the lowest viscosity? large, polar molecules small, nonpolar molecules small, polar molecules large, nonpolar molecules