Deep-sea divers often breathe a mixture of helium and oxygen to avoid getting the "bends" from breathing high-pressure nitrogen. the helium has the side effect of making the divers' voices sound odd. although your vocal tract can be roughly described as an open-closed tube, the way you hold your mouth and position your lips greatly affects the standing-wave frequencies of the vocal tract. this is what allows different vowels to sound different. the "ee" sound is made by shaping your vocal tract to have standing-wave frequencies at, normally, 270 hz and 2300 hz. what will these frequencies be for a helium-oxygen mixture in which the speed of sound at body temperature is 750 m/s? the speed of sound in air at body temperature is 350 m/s.

0.69444 m, 0.08152 m, 0.32407 m, 0.03804 m

Explanation:

v = Velocity of sound

f = Frequency

Length of vocal tract is given by

At f = 270 Hz v = 750 m/s

At f = 2300 Hz v = 750 m/s

At f = 270 Hz v = 350 m/s

At f = 2300 Hz v = 350 m/s

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.