Aznpocki

I was wondering how the 30day unlimited metro card works. when does the 30day time start? right when you buy it or first time you use it. For example if you buy two 30day cards at the same time, could you use one for one month and then use the other for the next month when the first card expires?

would it stay the same after the metrocard fare increase in december?

can someone help me answer these questions? answers to just one would be fine

1) The vapor pressure of water at 20 °C is 17.5 torr. A 16.7% solution of the nonvolatile solute ethylene glycol, C2H4(OH)2, in water is prepared. Calculate the vapor pressure of the solution to three significant figures.

2) At 21.0 °C, a solution of 17.80 g of a nonvolatile, nonpolar compound in 33.89 g of ethylbromide, C2H5Br, had a vapor pressure of 319.1 torr. The vapor pressure of pure ethyl bromide at this temperature is 400.0 torr. What is the molar mass of this compound?

(1) Calculate the pH of 0.63 M KNO2. What is the concentration of HNO2 in the above solution?

(2)What is the pH of a 0.21 M solution of arsenic acid, H3AsO4? In this solution, what are the concentrations of H2AsO4- and HAsO42

So i was thinking of getting this. Can anyone tell me about their experience with this? and the site says that the material prevents chlorine and other things from getting into the tank i was wondering if this was true or do i still need to use de-chlorinator?

Has anyone ever used this to clean a fishtank? How exactly does it work? Since it puts the water straight from sink into the tank what happens to the chlorine, would it go in the tank?