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O-level CIE Nov 2017

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  • hoay's Avatar
    189 posts since Jul '11
    • Which statement is correct?

      A   ammonia is produced when an ammonium salt is warmed with dilute HCl

      B   Amphoteric oxides are oxides of certain metals.

      C   a neutral solution doe not contain hydroxide ions.

      D   Soil with high pH can be neutralized by adding lime, Ca(OH)2.

       

      The answer is B. A and D are clearly wrong. But C is wrong here. A neutral solution has pH of 7 means No H+ nor OH- ions. But its wrong.What is a neutral solution then? and does it cintain OH-.Please explain in the jusridiction of O-level.

  • JonathanLeongCK's Avatar
    9 posts since Jan '18
    • Originally posted by hoay:

      Which statement is correct?

      A   ammonia is produced when an ammonium salt is warmed with dilute HCl

      B   Amphoteric oxides are oxides of certain metals.

      C   a neutral solution doe not contain hydroxide ions.

      D   Soil with high pH can be neutralized by adding lime, Ca(OH)2.

       

      The answer is B. A and D are clearly wrong. But C is wrong here. A neutral solution has pH of 7 means No H+ nor OH- ions. But its wrong.What is a neutral solution then? and does it cintain OH-.Please explain in the jusridiction of O-level.

      Hello,

       

      Indeed, option C is wrong. 

      A neutral ion actually contains the same concentration of OH- and H+. It is the same concentration of OH- and H+ ion that result in a pH of 7. 

       

      Regards,

      Jonathan Leong CK

  • hoay's Avatar
    189 posts since Jul '11
    • but if there are Hydroegn and hydroixe ions then wont they react to produce water, leaving bedhind no OH- ions?

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    H2 Chemistry @ BedokFunland JC (near VJC & TJC)
    UltimaOnline's Avatar
    15,001 posts since May '05
    • Originally posted by hoay:

      but if there are Hydroegn and hydroixe ions then wont they react to produce water, leaving bedhind no OH- ions?


      Equilibrium.

  • hoay's Avatar
    189 posts since Jul '11
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