1. a gas that has a volume of 28 l, a temperature of 45 °c, and an unknown pressure has its volume increased to 34 l and its temperature decreased to 35 °c. if the pressure is measured after the change to be 2.0 atm, what was the original pressure of the gas?
a. 4.1 atm
b. 3.2 atm
c. 2.5 atm
d. 1.6 atm
2. an unknown volume of gas has a pressure of 0.50 atm and temperature of 325 k. if the pressure is raised to 1.2 atm and the temperature decreased to 320 k, giving a new volume of 48 l, what was the initial volume?
a. 140 l
b. 65 l
c. 87 l
d. 120 l

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

Astudent made a graph plotting the progress of a reaction over time. the student forgot to label the y-axis of the graph. a graph is shown with two graph lines. one graph line starts at a higher position on the y axis and slopes downwards towards the right. the other graph line starts at a lower position on the y axis and slopes upwards towards the right. the two graph lines stop short of intersecting each other and continue as separate lines which gradually become straight and parallel to the x axis. a vertical line is shown at a point where the two graph lines finally became parallel to the x axis. this vertical line is labeled equilibrium. the title on the x axis is time and an arrow pointing towards the right is shown above time. the title on the y axis is left blank. what best explains the label that the student should use on the y-axis? amount, because as the amount of product decreases, the amount of reactant increases over time. reaction rate, because forward and backward reaction become equal at equilibrium. amount, because the amounts of reactants and products become constant after equilibrium is reached. reaction rate, as the rate of forward reaction increases and rate of backward reaction decreases over time.

Hey guys so i need to know what is _nh3+> nh4oh ~chemistry~