How many moles is 1 x 10^9 molecucles of o2

When a chemist collects hydrogen gas over water, she ends up with a mixture of hydrogen and water vapor in her collecting bottle. if the pressure in the collecting bottle is 97.1 kilopascals and the vapor pressure of the water is 3.2 kilopascals, what is the partial pressure of the hydrogen?

The standard emf for the cell using the overall cell reaction below is +2.20 v: 2al(s) + 3i2(s) → 2ai3+(aq) + 6i-(aq) the emf generated by the cell when [ai3+] = 3.5 × 10-3 m and [i-] = 0.015 m is v. the standard emf for the cell using the overall cell reaction below is +2.20 v: 2al(s) + 3i2(s) 2ai3+(aq) + 6i-(aq) the emf generated by the cell when [ai3+] = 3.5 × 10-3 m and [i-] = 0.015 m is v. 2.36 2.24 2.21 2.51 2.04

An isotope undergoes radioactive decay. the new isotope that forms has an atomic number fhat is 2 less than the original isotopes. which kind of decay has occured and how do you know