substances T, when heated in air, produces a brown gas that turn blue litmus paper red. The residue is a brown solid when hot and yellow solid when cold. Substances T may be
A. zinc carbonate
B. lead (II) carbonate
C. zinc nitrate
D. lead (II) nitrate

The eqn terbalik

But when you add barium carbonate to sodium chloride, you should get sodium carbonate and barium chloride

......
You're confusing me.
It's irrelevant with the question.

D

brown gas, litmus paper blue --> red : nitrogen dioxide
brown solid when hot, yellow solid when cold --> lead (ii) oxide

This post has been edited by IamjustME: Nov 8 2008, 11:03 PM

you sure boh ? this is not a reverse chemical equation

Ans is D since NO2 is brown.

why B cant?

and ..."the residue is a brown solid when hot and yellow solid when cold" shows it is Pb

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Added on November 8, 2008, 10:59 pmno Nitrogen leh

This post has been edited by work_tgr: Nov 8 2008, 10:59 PM

Agree.
Chemical Equation doesn't go 2 ways, unless the equation has the two way arrows.

D.

Pb² ion - brown when hot, yellow when cold (Why? Memorize it, it's the nature)
NO₃⁺ ion - When heated, NO₂ (Nitrogen dioxide) is formed. It's acidic, thus changing the litmus paper

tis is lead (II) oxide?

It applies to all Lead (II) xxxx solid.

So, should not refine to PbO only.
The best way to say is Pb²⁺ ion causing this nature.

This post has been edited by HotChocolate: Nov 8 2008, 11:02 PM

yes. My bad.

T = Pb(NO₃)₂

I think ... not really. E.g PbCO3 when heated it will release CO2

oh..so the question is asking abt the initial substances is what? i thought it's asking abt the product

No, its asking about the product. The residue is lead (II) oxide

initial reactant is lead(II) nitrate salt. only lead OXIDE is brown when hot yellow when cold. only zinc OXIDE is yellow when hot white when cold.

Yes, initial substance mate . Read carefully.

btw..

http://wiki.answers.com/Q/Ionic_Equation_f...odium_carbonate

Can this be trusted? It might be answered by non-pros

No lah ... reactant lah.

Wrong one zinc oxide is yellow when hot, white when cool