Influence01:
1.A (not sure)
2.C (group 1 metals like sodium, potassium and ammonia forms soluble salts)
3.B (Al2O3 is an amphoteric oxide)
4.A (not sure)
; D

labodinho:
4)If 24.4g of Lead(ii)trioxonitrate(v) were dissolved in 42g of
distilled water at 20DCelcius,calculate the solubility of solute in
gdm^-3
A)58.100
B)581.000
C)0.581
D)5.810

Dr. Laz'Devitan:


Recall that the density of water is 1g/cm^3,so 42g of water obviously is also 42cm^3 of water!
42cm^3 of water contains 24.4g of Pb
1000cm^3 will contain (1000 * 24.4)/42

So, SOLUBILITY=581g/dm^3

Dr. Laz'Devitan:
For those of u mailing me.....please get to know that nairaland does not send those emails,so i did not c any of them!

Dr. Laz'Devitan:


Problems with your question
1)Plane mirrors don't magnify objects,that's y u observe that you appear
of same size in a mirror...So plane mirrors dont cause magnification
2)Plane mirror don't have focal point......so,your question is baseless!

Mirrors notable for causing MAGNIFICATION are

CONCAVE and CONVEX Mirrors

They are SPHERICAL and not PLANE!

Dr. Laz'Devitan:


Once the value has exceeded it,you don't have to it again...u use the one lesser....If you observe my working....u shall discover,i did not make use of it!

Swagalord18:
NO, THERE'Z NOTHING WRONG WITH THE QUESTION,
In plane mirrors, image distance(v) and object distance(u) are equal, ...so their quotient is 1.0
hence,
the answer is (B) 1.0

i hope you understand, francisTony and Devitan

Dr. Laz'Devitan:


As much as i know,plane mirrors don't have magnification........this is becos the object and the image appear same as possible as i inferred earlier!.......

Swagalord18:
+yawns+ ......and thats the reason why the magnification is always 1.0, ..it neither magnifies nor diminishes, ....the object distance is 10, so the image distance will be 10, ....
Magnification = ^10cm/_10cm = 1.0, ....its that simple

great.david:
More power to your elbow @ dr. Laz and all other gurus in da house.
Let quickly take our brush with these;
math:
Integrat: (2x + 4 / x^2 + 4x + 5) + dx
chem:
on heating a concentrated HCl liquid,what type of gas is evolved, and what happens to the concentration of the acid
phy:
*name the two type of lens(es) used in an astronomical telescope

great.david:
i agree with swagalord.......but the fact still remains that plane mirrors don't magnify...

great.david:

chem:
on heating a concentrated HCl liquid,what type of gas is evolved, and what happens to the concentration of the acid

aysuccess99: @oga great david, I didn't understand your question wella, but I hope other guru would answer that chemistry question.

Swagalord18:

labodinho: Guys are boiling here,let's go there...

1) 2H2(g) + O2(g)------>2H2O(g)

In the reaction above,what volume of hydrogen would be left over when 300cm^3 of oxygen and 1000cm^3 of hydrogen are exploded in a sealed tube?

NB.-The Numbers In front of the equation are subscript.

2)A piece of filter paper moistened with Lead(ii)ethanoate solution turns black when the paper is dropped into a gas jar containing an unknown gas.The gas is likely to be

A)Sulphur(iv)oxide
B)Hydrogen chloride
C)Sulphur(vi)oxide
D)Hydrogen sulphide

3)What number of moles of Cu^2+ will be deposited by 360 coulombs of electricity?

A)5.36 * 10^-4 mole
B)1.87 * 10^-3 mole
C)9.35 * 10^-4 mole
D)3.73 * 10^-3 mole




Tho they are all simple,just manage it ma gurus.Show workings where necessary.

Ai-bi-ke:
500cm3 of oxygen was collected over water at 30 degCelcius and 752mmHg pressure. What is the volume of dry Oxygen at S.t.p
(vapour pressure of water at 30 degcelcius=32mmHg)

according to Dalton's law,
total pressure = sum of partial pressures
so 752(total pressure) = 32(water pressure) + x(oxygen pressure)
x = 752 - 32 = 720mmHg(oxygen pressure)
^p1V1/_T1 =
^p2V2/_T2 (gas equation)
p1 = 720 mmHg
V1 = 500 cm³
T1 = (30 + 273)K = 303K
p2 = s.p = 760 mmHg
V2 =
T2 = s.t = 273K

v2 = ^p1V1T2/_p2T1
= ^{720 x 500 x 273}/_{760 x 303}
=
426.78 cm³

Ai-bi-ke:
In d below reaction,.what is d value of x?Cr2O7^2- + 14H^+ + xe^-=2cr^3+ + 7H2O
pls waht I need most is aw u get dat value,...xo ur workings is all I need

Swagalord18:
according to Dalton's law,
total pressure = sum of partial pressures
so 752(total pressure) = 32(water pressure) + x(oxygen pressure)
x = 752 - 32 = 722mmHg(oxygen pressure)
^p1V1/^T1 =
^p2V2/^T2 (gas equation)
p1 = 722 mmHg
V1 = 500 cm³
T1 = (30 + 273)K = 303K
p2 = s.p = 760 mmHg
V2 =
T2 = s.t = 273K

v2 = ^p1V1T2/_p2T1
= ^{722 x 500 x 273}/_{760 x 303}
=
426.78 cm³

great.david:
balance the charge at both sides.....
Total no of charge in the RHS=> +14 + (-2)= +12
total no of charge in the LHS=> 2 *(+3)= +6
: . RHS must be equal to LHS
i.e +12 + 6e^- = +6
x=6
thus, we have the equation as:
Cr2O7^2- + 14H^+ + 6e^-=2cr^3+ + 7H2O

Ai-bi-ke:
if dats d matter,...den what abt dis
2ClO3^- +12H^+ +12e^-=2Cl^- + 6H2O...does it mean iT is nt correct!....

Swagalord18:
according to Dalton's law,
total pressure = sum of partial pressures
so 752(total pressure) = 32(water pressure) + x(oxygen pressure)
x = 752 - 32 = 722mmHg(oxygen pressure)
^p1V1/^T1 =
^p2V2/^T2 (gas equation)
p1 = 722 mmHg
V1 = 500 cm³
T1 = (30 + 273)K = 303K
p2 = s.p = 760 mmHg
V2 =
T2 = s.t = 273K

v2 = ^p1V1T2/_p2T1
= ^{722 x 500 x 273}/_{760 x 303}
=
426.78 cm³

Swagalord18:
it is correct

great.david:
P1 = 720 mmHg and not 722 mmHg......typographical error