your mommy buys you a helium balloon at a circus. It has a volume of 4.00 liters at stp. what mass of helium, express in gram, does this balloon contain? answer

Abeaker with 2.00×102 ml of an acetic acid buffer with a ph of 5.000 is sitting on a benchtop. the total molarity of acid and conjugate base in this buffer is 0.100 m. a student adds 4.70 ml of a 0.360 m hcl solution to the beaker. how much will the ph change? the pka of acetic acid is 4.740.