Comments on: O Levels Chemistry – Selected Exam Questions

By: png

png — Sun, 17 Jan 2010 14:00:32 +0000

I hope my answers are not too late. For question 1, CO2 will not be accepted because in our air, this is already a small percentage of CO2, so we do not consider it that acidic. SO2 is chosen because SO2 forms H2SO3 in water which is much more acidic than HCO3-, thus it is much safer to choose SO2.

As for question 2, I learnt it in class 2/3 years ago. It’s a reaction that is not required of O level candidates. (:

By: sean

sean — Thu, 15 Oct 2009 05:34:19 +0000

Hi Al Nasr Ahmed,

See my reply to Marcus & Jie below.

All the best to your Chemistry,
Sean Chua =)

By: sean

sean — Thu, 15 Oct 2009 05:33:42 +0000

Hi Marcus,

Your reasoning for the question on Zinc Oxide is correct.
Keep it up!

For the question on photography chemistry, your steps in analysis is also spot on. Answer would be options 2 in which Ag+ ions has been reduced to Ag after taking in electrons.

Hope this information helps.

To Your Academic Success in Chemistry,
Sean Chua =)

By: sean

sean — Thu, 15 Oct 2009 05:28:32 +0000

Well Done!

I like your explanations on this question posted by Al Nasr Ahmed.

Keep up the good work!
Sean Chua =)

By: sean

sean — Thu, 15 Oct 2009 04:50:14 +0000

Hi Shahbuz,

Please go ahead and send me an email if you have chemistry questions that you would like to discuss with readers in the humble chemistry blogsite.

Thanks,
Sean Chua