Opted Pratice Test Chemistry Stumpers

[OATeater]

Hey everyone,

I just practised myself on Chemistry from the opted site.. I got a 370 under "ideal conditions" (ie at home in my pyjamas haha).

There are a couple that are throwing me for a loop, I can't seem to figure out why I got them wrong:

1) Number 44: " IF the mass percent of oxygen in a nitrogen oxygen compund is known, given the mass percent of oxygen, all of the following are needed to determine the molcular formula of a nitrogen-oxygen compound EXCEPT one. Which one is this EXCEPTION?

A) Atomic Mass of Nitrogen
B) Atomic Mass of oxygen
c) avogadro's number
d) empirial formula
e) molar mass of the compound.'

and 2)

A 0.60 M solution is made by dissolvign solid compound X in water. After 10seconds, the concentraion of X is 0.40 M. All of the follwoing could account for tthese results EXCEPT ONE. Which on is this EXCEPTION?

A) Precipitation
B) Neutralization
C) Evaporation
D) Decomposition
E) Disproportionation

The test says its

*Spoiler warning*














1) D - Empirical formula. I dont know how thats true..i certanly use Emp. formula do to my molecular formula calculation ... I would have said "C" avogadros's number.

2) A - Precipitation. I'm VERY confused at this one.

Any help will be rewarded with a cookie.

Cheers.

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[luvblueyes]

Hey everyone,

I just practised myself on Chemistry from the opted site.. I got a 370 under "ideal conditions" (ie at home in my pyjamas haha).

There are a couple that are throwing me for a loop, I can't seem to figure out why I got them wrong:

1) Number 44: " IF the mass percent of oxygen in a nitrogen oxygen compund is known, given the mass percent of oxygen, all of the following are needed to determine the molcular formula of a nitrogen-oxygen compound EXCEPT one. Which one is this EXCEPTION?

A) Atomic Mass of Nitrogen
B) Atomic Mass of oxygen
c) avogadro's number
d) empirial formula
e) molar mass of the compound.'

and 2)

A 0.60 M solution is made by dissolvign solid compound X in water. After 10seconds, the concentraion of X is 0.40 M. All of the follwoing could account for tthese results EXCEPT ONE. Which on is this EXCEPTION?

A) Precipitation
B) Neutralization
C) Evaporation
D) Decomposition
E) Disproportionation

The test says its

*Spoiler warning*














1) D - Empirical formula. I dont know how thats true..i certanly use Emp. formula do to my molecular formula calculation ... I would have said "C" avogadros's number.

2) A - Precipitation. I'm VERY confused at this one.

Any help will be rewarded with a cookie.

Cheers.

I just did this too, but I only got a 340 haha. I also picked Avagadro's number and got it wrong...I would like to know the answer to this too!!

I have a a couple of the physics ones I am stuck on. Maybe tomorrow if I still can't figure them out I will post them up! Have you done that section yet?

When are you taking the OAT??

 

[OATeater]

Throw them up then . Yea I've done physics I'm ok....a couple I'm still stumped on of course.


I write friday. Scared? Yes. Want to get it over with? YES.