onlyme07:

Maybe yours but my brother's own which said no login credentials prior the update went through when I read the update. Make sure your Surname is in capital. Best of luck bro.

when did he reg? And when,whr and how did u read d update?

TeflonBlixx:


NaOH + H20 ----- Na+ + OH-

Find the hydrogen ion concentration

Ph = -log(H+)

10.5 = -(logH+)

H+ = Antilog -10.5

= Antilog -11 x Antilog +0.5
= 1 x 10^ -11 x 3.1622
= 3.16 x 10^-11 M

Volume = 0.8dm^-3

Therefore, mass conc = molar mass x molar conc

x/0.8 = 40 x 3.16 x 10^ -11

x = 1.0112 x 10^-9g

Orezy5, how correct is this?

This is wrong. The question is to find mass. Not mass conc.
Then you used the H conc instead of OH concentration as it is NaOH.

I got 0.0202g though. Don't know if I'm correct

esivue007:
when did he reg? And when,whr and how did u read d update?

I read the update on friday evening here on NL and registered same day. You can check the post you first quoted me. He registered same

pls in what format should i upload my o level results on UI portal, when i checked my result i didnt print it, instead i saved it as pdf, so pls is it advisable to use .pdf format? PLS I NEED ANS

onlyme07:

I read the update on friday evening here on NL and registered same day. You can check the post you first quoted me. He registered same

though i dont really understand the update you're talking abt,can u pls refer me to the update page's no? And i havent seen any aspirant dat did coc and has registered even on fb,and acordin 2 d info frm ui admin office via my bro 2 me,they said dat d update will begin dis week,but since u said u've reg, "peace".

Adolak:


This is wrong. The question is to find mass. Not mass conc.
Then you used the H conc instead of OH concentration as it is NaOH.

I got 0.0202g though. Don't know if I'm correct

Holee shit. . Thanks man, totally skipped my mind.

Eben331:
(1) If 21g of alcohol of density 0.7g/cm^3 is mixed with 10g of water, what would be the density of the resulting mixture? (a) 780g/cm^3 (b) 0.78g/cm^3 (c) 30g/cm^3 (d) 10g/cm^3 (2) For a particle having an x coordinate varies in time according to the expression x=4t-2t^2, the instantaneous velocity of the particle at t=2.5secs is (a) 12m/s (b) 6m/s (c) 0m/s (d) 10m/s PLS SHOW UR WORKINGS!!

Mass of Alcohol -- 21g
Density -- 0.7g/cm^3

Volume -- Mass/Density

-- 21/0.7
-- 30cm^3

Mass of Water -- 10g
Density -- 1g/cm^3

Volume--Mass/Density

-- 10cm^3

Density of the mixture -- Total mass of the mixture/Total volume of the mixture

21+10/30 + 10

-- 0.775g/cm^3
--- 0.78g/cm^3

2. B

Adolak:


This is wrong. The question is to find mass. Not mass conc.
Then you used the H conc instead of OH concentration as it is NaOH.

I got 0.0202g though. Don't know if I'm correct

can u pls show the workings??

TeflonBlixx:



Mass of Alcohol -- 21g
Density -- 0.7g/cm^3

Volume -- Mass/Density

-- 21/0.7
-- 30cm^3

Mass of Water -- 10g
Density -- 1g/cm^3

Volume--Mass/Density

-- 10cm^3

Density of the mixture -- Total mass of the mixture/Total volume of the mixture

21+10/30 + 10

-- 0.775g/cm^3
--- 0.78g/cm^3

2. B

pls show the workings to the second question.

micskales:
pls in what format should i upload my o level results on UI portal, when i checked my result i didnt print it, instead i saved it as pdf, so pls is it advisable to use .pdf format? PLS I NEED ANS

I will advise that you should go to cybercafe. They will help you there.

A heating coil of resistance 30ohm is connected to a 240volt supply for 300seconds to boil a quantity of water in a vessel of heat capacity 200j/k. If the initial temperature of the water is 20degree celsius and its specific heat capacity is 4200j/kg/k. Calculate the mass of water in the vessel. (answer=1.67kg. Please solve until you get this answer)


2. A transformer is required to supply 0.2ampere at 100volt from the secondary using a primary voltage of 250volt. if the primary has 120turns, calculate the number of secondary turns and the primary current assuming the transformer is 100% efficient.(answer= 480turns, 0.8ampere. pls solve and get this answer) cc indomixx eben331 drbestjc aceed

BiafranDel:
A heating coil of resistance 30ohm is connected to a 240volt supply for 300seconds to boil a quantity of water in a vessel of heat capacity 200j/k. If the initial temperature of the water is 20degree celsius and its specific heat capacity is 4200j/kg/k. Calculate the mass of water in the vessel. (answer=1.67kg. Please solve until you get this answer)


2. A transformer is required to supply 0.2ampere at 100volt from the secondary using a primary voltage of 250volt. if the primary has 120turns, calculate the number of secondary turns and the primary current assuming the transformer is 100% efficient.(answer= 480turns, 0.8ampere. pls solve and get this answer) cc indomixx eben331 drbestjc aceed

. I keep getting 1.71 for number one. Dunno, where I'm getting it wrong.
2. I got 48 instead of 480 and 0.08A instead of 0.8....

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Indomixx:
. I keep getting 1.71 for number one. Dunno, where I'm getting it wrong.
2. I got 48 instead of 480 and 0.08A instead of 0.8....

I think you are correct for the number 2. Got same answers. It must be error from the textbook then.

Please show the workings for the number one. I didn't get the answer too but yours is even close.

BiafranDel:


2. A transformer is required to supply 0.2ampere at 100volt from the secondary using a primary voltage of 250volt. if the primary has 120turns, calculate the number of secondary turns and the primary current assuming the transformer is 100% efficient.

What I get are Ns=48 turns and Ip=0.08A

BiafranDel:
A heating coil of resistance 30ohm is connected to a 240volt supply for 300seconds to boil a quantity of water in a vessel of heat capacity 200j/k. If the initial temperature of the water is 20degree celsius and its specific heat capacity is 4200j/kg/k. Calculate the mass of water in the vessel.

R=300 ohms, V=240v, t=300s, initial temperature T1=20^oC, final temperature T2=100^oC (since it is at boiling point), heat capacity of vessel C=200J/K, specific heat capacity of water c=4200J/kg/K, mass of water in the vessel m=? >>> Note that both the water and vessel have the same initial and final temperature >>> Heat gained by water + heat gained by vessel = Heat lost by coil >>> mc(T2-T1) + C(T2-T1) = V^2t/R >>> m*4200(100-20) + 200(100-20) = (240^2*300)/30 >>> m*4200*80 + 200*80 = 57600*10 >>> m*336000 + 16000 = 576000 >>> m*336000 = 576000-16000 >>> m*336000 = 560000 >>> m=560000/336000 >>> m=1.667kg >>> m=1.67kg (approx)

My younger sister is having problem with her registration. The Subjects aren't loading also no place to upload o level any solution would be highly appreciated. Thanks.

http://ui.edu.ng/news/20182019-direct-entry-admission-exercise

UI Direct entry applicants

A body moves over one fourth of a circular arc in a circle of radius r. The magnitude of distance travelled and displacement will be ?

is it possible to cross from education and political science to political science in 200 level

need ur reply ASAP palz

Hi,a little help needed here,the website for registration of the exam is not through,what do i do?

Iambaj:
My younger sister is having problem with her registration. The Subjects aren't loading also no place to upload o level any solution would be highly appreciated. Thanks.

I will advise that she should go to cybercafe. They will help her out there.

Dkfpaul:
is it possible to cross from education and political science to political science in 200 level

need ur reply ASAP palz

Art students are in a better position to answer this question.

Ebencoula14:
Hi,a little help needed here,the website for registration of the exam is not through,what do i do?

It may be due to many candidates trying to register. Keep trying it or you can try doing it at midnight.

Gracy3535:
A body moves over one fourth of a circular arc in a circle of radius r. The magnitude of distance travelled and displacement will be ?

1 circle = 2pie = teta...where teta=angular displacement. >>> 1/4 of circle = 1/4*2pie = pie/2 >>> therefore teta = pie/2 >>> angular displacement = pie/2...distance s = teta*radius >>> distance s = pie/2*r = pie*r/2.

Eben331:
(1) If 21g of alcohol of density 0.7g/cm^3 is mixed with 10g of water, what would be the density of the resulting mixture? (a) 780g/cm^3 (b) 0.78g/cm^3 (c) 30g/cm^3 (d) 10g/cm^3 (2) For a particle having an x coordinate varies in time according to the expression x=4t-2t^2, the instantaneous velocity of the particle at t=2.5secs is (a) 12m/s (b) 6m/s (c) 0m/s (d) 10m/s PLS SHOW UR WORKINGS!!

Differential function

x = 4t - 2t^2

v = dx/dt = 4 - 4t

At time = 2.5s

4 - 4 x2.5

4 - 10

= -6m/s

Eben331:
R=300 ohms, V=240v, t=300s, initial temperature T1=20^oC, final temperature T2=100^oC (since it is at boiling point), heat capacity of vessel C=200J/K, specific heat capacity of water c=4200J/kg/K, mass of water in the vessel m=? >>> Note that both the water and vessel have the same initial and final temperature >>> Heat gained by water + heat gained by vessel = Heat lost by coil >>> mc(T2-T1) + C(T2-T1) = V^2t/R >>> m*4200(100-20) + 200(100-20) = (240^2*300)/30 >>> m*4200*80 + 200*80 = 57600*10 >>> m*336000 + 16000 = 576000 >>> m*336000 = 576000-16000 >>> m*336000 = 560000 >>> m=560000/336000 >>> m=1.667kg >>> m=1.67kg (approx)

What about the mass of the vessel?

[qu of water in the ves


2. A transformer is required to supply 0.2ampere at 100volt from the secondary using a primary voltage of 250volt. if the primary has 120turns, calculate the number of secondary turns and the primary current assuming the transformer is 100% efficient.(answer= 480turns, 0.8ampere. pls solve and get this answer) cc indomixx eben331 drbestjc aceed[/quote]






Is=0.2

Vs=100

Vp=250


Ns=


Ip=


Vs/Vp=Ns/Np=Ip/Is


100/250=Ns/120


Ns=120×100/250


Ns=48 turns



Vs/Vp=Ip/Is


100/250=Ip/0.2



Ip=100×0.2/250


Ip=0.08A

Eben331:
1 circle = 2pie = teta...where teta=angular displacement. >>> 1/4 of circle = 1/4*2pie = pie/2 >>> therefore teta = pie/2 >>> angular displacement = pie/2...distance s = teta*radius >>> distance s = pie/2*r = pie*r/2.

correct

TeflonBlixx:

Differential function
x = 4t - 2t^2
v = dx/dt = 4 - 4t
At time = 2.5s
4 - 4 x2.5
4 - 10
= -6m/s

Thanks bro.

TeflonBlixx:


What about the mass of the vessel?

Since what we were given was heat capacity of the vessel and not the specific heat capacity of the vessel, so the mass of the vessel is not needed...from the formula of heat capacity: H=C(T2-T1) >>> C=H/(T2-T1).

A Physics student standing on the edge of a cliff throws a stone vertically downward with an initial speed of 10m/s. The instant before the stone hits the ground below, it is travelling at a speed of 30m/s. If the physics student were to throw the rock horizontally outward from the cliff instead, with the same initial speed of 10m/s, what is the magnitude of the stone just before it hits the ground? (a) 10m/s (b) 20m/s (c) 30m/s (d) 40m/s. PLS SHOW UR WORKINGS!!