Auniform narrow tube 1.80 m long is open at both ends. it resonates at two successive harmonics of frequencies 280 hz and 300 hz. (a) what is the fundamental frequency(hz)? (b) what is the speed of sound in the gas in the tube(m/s)?

 Harmonics are integer multiples of the fundamental frequency. 

I found the greatest common factor of 280 Hz and 420 Hz, and that was 140 Hz. Therefore, I knew that this was the fundamental frequency. (280 Hz and 420 Hz are the second and third harmonics, respectively) 

The formula for the fundamental frequency of an open pipe is 

f= (v/2L) 
where v is the velocity of the gas inside the tube and L is the length of the tube. 
I assume that I'm ignoring end corrections in this calculation. 

f= 140 Hz 
v= unknown 
L= 1.85 meters 

140 = (v)/ (2*1.85) 
v= (140)(2)(1.85)= 518 m/s

Acetic acid  /əˈsiːtɪk/, systematically named  ethanoic acid  /ˌɛθəˈnoʊɪk/, is a colourless liquid  organic compound  with the  chemical formula  ch3cooh (also written as ch3co2h or c2h4o2). when undiluted, it is sometimes called  glacial acetic acid.  vinegar  is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. acetic acid has a distinctive sour taste and pungent smell. in addition to household vinegar, it is mainly produced as a precursor to  polyvinyl acetate  and  cellulose acetate. it is classified as a  weak acid  since it only partially  dissociates  in solution, but concentrated acetic acid is corrosive and can attack the skin.acetic acidnamespreferred iupac nameacetic acidsystematic iupac nameethanoic acidother namesvinegar (when dilute); hydrogen acetate; methanecarboxylic acid[1][2]identifierscas number64-19-7  3d model (jsmol)interactive image3dmetb00009 reference506007chebichebi: 15366  chemblchembl539  chemspider171  drugbankdb03166  echa infocard100.000.528ec number200-580-7e numbere260  (preservatives)gmelin reference1380iuphar/bps1058keggd00010  meshacetic+acidpubchem  cid176rtecs numberaf1225000uniiq40q9n063p  un number2789inchiinchi=1s/c2h4o2/c1-2(3)4/h1h3,(h,3,4)  key:   qtbsbxvteameqo-uhfffaoysa-n  smilescc(o)=o

It indicates no change in temperature and the process of matter changing its state