When more than one variable in an experiment is changed at a time, the scientist
a.
cannot tell which change produced the results.
b.
cannot accurately measure both variables at the same time.
c.
needs to conduct more trials in order to get conclusive results.
d.
made a systematic error that needs to be corrected.

If the density of water is 1.0 g/cm3, which of these materials would float in water, based on their densities? check all that apply. aluminum cork iron lead wax

Since the gas in your graduated cylinder is a mixture of butane and water vapor, you must determine the partial pressure of the butane, pbutane, alone. to do this, consult a reference and record the partial pressure of the water vapor, pwater, at the temperature you recorded. use the following formula to compute the partial pressure of the butane. pbutane = atmosphere - pwater use the following combined gas law formula and compute the volume that the butane sample will occupy at stp. (hint: convert both temperatures to kelvin.) pbutane x voriginal = pstandard x vfinal troom tstandard use the following ratio and proportion formula to determine the mass of butane needed to occupy a volume of 22.4 l at stp. grams of butane you used “x” grams of butane ml of butane corrected to stp = 22,400 ml compute the theoretical molar mass of butane based on its formula and the atomic masses on the periodic table. compare your experimental results from #3 to the theoretical value of #4, computing a percent error of your findings using this formula: % error = measured value - accepted value x 100 accepted value use the following ratio and proportion formula to determine the mass of butane needed to occupy a volume of 22.4 l at stp. need asap

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?