What part of an original isotope's number of atoms remains after two half lives?

A helium balloon has a volume of 2.5 L. When heated to 343.5K the pressure of the gas is 66.7 kPa. How many moles of He gas would there be?

9 Which term represents the attraction one atom has for the electrons in a bond from another atom? (1) electronegativity (2) electrical cond1lctivity (3) first ionization energy (4) mechanical energy

As the elements in period 2 of the Periodic Table are considered in order from left to right, which property generally decreases? 1) Atomic radius 2) Electronegativity 3) ionization charge 4) Nuclear charge

A compound composed of only c and f contains 17.39 c by mass. what is its empirical formula

The equilibrium constant for the reaction of fluorine gas with bromine gas at 300 K is 54.7 and the reaction is: Br2 (g) + F2 (g) ⇔ 2 BrF (g) What is the equilibrium concentration of fluorine if the initial concentrations of bromine and fluorine

Which common material is an example of a polyamide?

A particular brand of gasoline has a density of 0.737 g/mL at 25 ∘ C. How many grams of this gasoline would fill a 12.8 gal tank (1US gal=3.78L) ?

A pump contains 0.5 l of air at 203 kpa. you draw back on the piston of the pump, expanding the volume until the pressure reads 50.8 kpa. what is the new volume of air in the pump? 0.2 l 1.0 l 2.0 l 4.0 l

How can there be snow near a giraffe's home This is actually science so yeah

If a sealed syringe that contains some gas in heated in which direction will the syringe plunger move