Page 444 - Chemistry eBook

27 Which class of compounds contains at least one element from Group 17 of the Periodic Table?
29 When a voltaic cel the
(1) anode (2) cathode
30 When dissolved yields
(1) hydrogen ions (2) hydronium io
(1) aldehyde (3) ester
(2) amine
(4) halide
Sample Regents Questions
28 In a propanal molecule, an oxygen atom is bonded with a carbon atom. What is the total number of pairs of electrons shared between these atoms?
(1) 1 (3) 3 (2) 2 (4) 4
Jan 2012 #28
Answer
Choice #2
Explanation: We know that this is an aldehyde because the molecule ends with ‘al’. Reffy, Table R (p. 8) shows that the functional group for aldehyde contains a double bond between the C and O. This means that 2 pairs of electrons (4 electrons) are shared.
If you forget that aldehydes end in ‘al’,
peek at Reffy, Table
R (p. 8), which gives the example for aldehyde, which ends with ‘al’. If you look extra close, you’ll realize that the example given is propanal!
i n
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