The half life of a certain substance is 28 years. how long will it take for a sample of this substance to decay to 78% of its orginal amount.

After 42 days a 2.0 g sample of phosphorus-32 contains only 0.25 g of the isotope. What is the half-life of phosphorus-32?

At which temperature do the molecules of an ideal gas have 3 times the kinetic energy they have at 32of?

The election configuration has of an element is 1s^2 2s^2 2p^1. How many valence electrons does the element have?

The name given to the substance formed when a liquid is miscible in another liquid.

How many electrons do you need to match the weight of a proton

Determine the number of moles of sulfur trioxide produced when 3.5 moles of oxygen gas is consumed in the reaction

For each of the following balanced oxidation-reduction reactions, (i) identify the oxidation numbers for all the elements in the reactants and products and (ii) state the total number of electrons transferred in each reaction. 1.

Hypervitaminosis is a serious health threat associated with excessive amounts of ingested fat-soluble vitamins. why do water-soluble vitamins not commonly pose the same threat?

Hydrogen is an element with two naturally occurring isotopes: 2 H and 3 H. This means that 2 H, which has a mass number of 2, has fewer than 3 H, which has a mass number of 3. True/False

C₂H₂ + O2 - CO₂ + H₂ How many moles of oxygen are necessary to react completely with 4.0 moles of propane (CH) ?