Which of the following substances may be condensed using a water-cooled condenser?
Substance Melting point/deg cel Boiling point/deg cel
A -120 -4
B -30 15
C 10 40
D 60 95
Eh, not sure what's the criteria needed for this to happen... my guess would be B. It would be great if someone could spell out the conditions for this to occur.
2. Tritium (symbol T) is an isotope of hydrogen. Which formula is incorrect for tritium compound?
NT3 CT4 BaOT T2O
The answer is definitely BaOT because the formula for the other 3 compounds are all correct. But why BaOT?
3. Next.
W is a non conductor of electricity in both solid and liquid state and when hit with a hammer, it doesn't change
X is a good conductor of electricity in both solid and liquid states and flattens when hit with a hammer
Y is a non-conductor in solid state but good conductor in liquid state, it shatters when hit with a hammer
What are W,X and Y?
2 possible options:
W - SiO2 X - Na Y - CuSO4
W - Br2 X - Zn Y - CaO
I think the answer is the first option because how do you test the malleability of Bromine? At least SiO2 doesn't change when hit with hammer. Weird to hit Br2 (liquid) with hammer. HAHA.
Lastly
The ratio of the number of atoms present in 5 g of Argon gas, Bromine gas , and Neon gas would be
A 1:1:1
B 2:1:1
C 2:2:1
D 2:4:1
Please explain to me how to calculate this.... do you find no. of moles and multiply with the avagadro constant?
Thanks!
1.When a substance is condensed, it is changes from gaseous to liquid state. When it is cooled using water-cooled condenser, the temperature will drop from around 27 to 0 deg cel. So substance B changes from gaseous state(at room temperature 27 deg cels) to liquid state (between 0 to 15 deg cels)
2. For all isotopes of hydrogen, they have the same number of electrons. So the anion they forms with oxygen will still have a charge of -1. e.g. OH- . Ba forms an cation of Ba2+. So it needs to 2 OH- to form an ionic compund with Ba2+(balance the charges). e.g. Ba(OH)2.
3. Bromide is liquid and it can't be hammered. SiO2 is sand by the way.
4.I'm not sure about that one.. I calculated using number of moles too and get this instead.
4 : 1 : 8
The ratio of the number of atoms present in 5 g of Argon gas, Bromine gas, and Neon gas would be :
Ar : Br2 : Ne
5/40 : 2x(5/160) : 5/20
0.125 : 0.0625 : 0.25
2 : 1 : 4
Answer : neither A, B, C, nor D.
>>> The ratio of the number of atoms present in 5 g of Argon gas, Bromine gas, and Neon gas would be
A 1:1:1
B 2:1:1
C 2:2:1
D 2:4:1 <<<
Hi everyone!
I still do not understand how to derive the answer for the last question.
Thanks!
Originally posted by anpanman:Hi everyone!
I still do not understand how to derive the answer for the last question.
Thanks!
U are given the mass of the gas which is 5g each. Divide 5g by their individual Mr and you will get their number of moles.
Since number of atoms is = to number of moles X 6.023 X 10^23, it would be sufficient to just get the ratio from the number of moles due to the constant not affecting the results.
Originally posted by dkcx:U are given the mass of the gas which is 5g each. Divide 5g by their individual Mr and you will get their number of moles.
Since number of atoms is = to number of moles X 6.023 X 10^23, it would be sufficient to just get the ratio from the number of moles due to the constant not affecting the results.
Yea, but I got 1:1:2 for my answer. Fits none of the options.
Originally posted by anpanman:
Yea, but I got 1:1:2 for my answer. Fits none of the options.
Please refer to UltimaOnline's answer. Did u use the Mr of Br or Br2 when you did your calculations? I assume you only use Br and not Br2.