₦airaland Forum

OGOJNR:
when a resistance R across a cell,the voltage across the terminals of the cell is reduced to two-thirds its nominal value.The internal resistance of the cell is .....
a.R/3 B.R C.2R/3 D.R/2

Not clear! What exactly is reduced? R, V or both?

becborn:
good evening bosses.....

evening bossress

horpeyemmi66:
*CHEMISTRY | ELECTROLYSIS 001


3. What volume of Oxygen measured at STP would be liberated by passing a current of 10A into a Hoffman's voltameter containing acidified water for 965 seconds?

A. 5.60 dm3

B. 0.560 dm3

C. 11.2 dm3

D. 1.12 dm3

1 mole of O2 = 4F = 22.4dm3
I.e 4*96500 = 22.4dm3
10*965 = x
x = 224*965/4*96500
x = 224/400
x = 56/100= 0.56dm3

horpeyemmi66:
*CHEMISTRY | ELECTROLYSIS 001

2. A current of 0.50A flows for 16mins 5seconds and deposits 0.163g of a metal X during the eletrolysis of an aqueous solution of a salt of the metal. What is the charge on the metal ion?

A. ±4
B. ±3
C. ±2
D. ±1

I = 0.5A, t = (16*60)+5 = 965s, m = 0.163g, M = 65, n = ?
From the relation
MQ = nFm
n = MIt/Fm
Therefore n = (65*0.5*965)/(96500*0.163)
n = 1.99, approximately +2

horpeyemmi66:
4. What mass of bromine would be produced during the electrolysis of molten lead(II) bromide in which 10.35g of lead was deposited?[Pb=207, Br=80]

A. 4.00g

B. 7.00g

C. 4.50g

D. 8.00g

mass of Br2 produced = 8.0g

horpeyemmi66:
*CHEMISTRY | ELECTROLYSIS 001

1. If the cost of electricity required to deposit 1g of aluminium is N4.00, how much would it cost to deposit 24g of copper?[Al=27, Cu=64]

A. ₦27.02

B. ₦37.02

C. ₦47.02

D. ₦57.02

Answer is #27. See workings in the picture below. To busy to type

OGOJNR:
pls,wich textbuks do u guys read for phy,chem,bio@horpe and mathefaro

hmm! Any available text. But New school and okeke are the longest serving texts for me.....

FrancisTony:
Umartins can you show workings on clear explanation for that number1

1. 2 dice are thrown together. What's the probability of getting a sum of 5?

Solution
======##=
The proper thing to do here is to draw the probability outcome table. And if study the table properly, we'll see that number of outcomes in which the sum of the numbers is five is 4(required outcome) and the total number of outcomes is 36. Therefore the answer 4/36 = 1/9
See picture below

enry54:
What about the case of circular motion?

Then it becomes centripetal acceleration. I guess we're talking about linear motion. And in the case of centripetal acceleration, there's no change in velocity and time ain't considered and that's why it's formula = v^2/r.
Totally different concept

Umartins1:
mathefaro



1/9



sum to infinity = a/ 1-r
16/7 = 4/ 1-r
16-16r= 28
-16r= 28-16
-16r= 12
r= -12/16
r= -3/4



x+y= 2(x-y)..... 1
xy=675........ 2

x+y= 2x-2y
x-2x=-2y-y
-x=-3y
x=3y........ (3)
xy=675...... (2)

Sub for x in eqn (2)
3y(y)= 675
3y²= 675
y²= 225
y²= 15²
y= 15

Sub for y in eqn (3)
15x=675
x= 675/15
x= 45

The father's age= 45years.




m₁= k

2y+3x=7
2y=7-3x
y= 7/2 - 3/2 x

M₂ = -3/2

When it is perpendicular,
M₁M₂ =-1
k * -3/2 = -1
-3k/2 = -1
-3k= -2
k= -2/-3
k= 2/3



9P₃
9!/ (9-3)!
9!/6!
9*8*7
504ways



a+2d= 4x-2y....... (1)
a+8d= 10x-8y...... (2)

Eqn (2)-(1)

6d= 6x-6y
6d= 6 (x-y)
d=x-y



from the 1st statement,
(a+b+c+d+e) / 5 = x
a+b+c+d+e= 5x.

From the 2nd statement,

(a+k+b+2k+c-k+d-2k+e)/ 5

(a+b+c+d+e+k+2k-2k) / 5

Since, a+b+c+d+e= 5x
(5x+k+2k-2k)/5
5x/5
=x




x= anti-log (3-y)




A= pi r²
22/7 * 2²
22/7*4
88/7 cm²




60/360 * 2pi r
1/6 * 2pi r
Pi r/3 cm.

you aced 8 of them

enry54:
If a body moves with a constant speed and at the same time undergoes an acceleration, What can you say about that ?

Not possible! For the fact that it's moving with a constant speed means it's speed is neither increasing nor decreasing. Hence no change in speed and acceleration us zero

Let's go easy with cheap math questions as we go to bed.

1. 2 dice are thrown together. What's the probability of getting a sum of 5?

2. The sum of an infinite geometric progression is 16/7 and the first term is 4. What's the common ratio?

3. A man is x years old while his son is you years old. The sum of their ages is twice the difference of their ages. If the product of their ages is 675. Find the age of the man

4. The line y = kx - 3 is perpendicular to the line 2y + 3x = 7. What's the value of k?

5. In how many ways can 9 people be seated if 3 chairs are available?

6. The third term of an A.P is 4x - 2y and the ninth term is 10x - 8y. Find the common difference

7. If the mean of the numbers a, b, c, D and e is x. What's the mean of the numbers a + k, b + 2k, c - k, d - 2k and e?

8. Make x the subject of the relation y = 3 - lnx

9. An equilateral triangle of side 2cm is inscribed in a circle. Find the area of the circle in terms of π.

10. The chord PQ of a circle is equal to the radius r of the circle. Find the length of the arc PQ in terms of r and π.

NB: These are excerpts from questions treated on whatsapp.
Good night folks

horpeyemmi66:
It's copy and paste job jare, all thanks to Google and Webcrawler!

ok

@horpeyemmi66, please do you use an android? If yes, which keyboard do you use that contains all these symbols?

OGOJNR:
itz linear expansivity,hw did it become superficial,sir..i dnt undastand

my brother, it's not linear expansivity. It's actually superficial because Its the cross sectional area of the the plug that needs to decrease to fit in into the hole and not the length. So if you calculate well, you'll get a temperature less than the given one in which the radius is 5cm. I hope it's clear now.
**Winks**
For me, I'm still at a birthday party(owo epo things) lol

horpeyemmi66:
*PHYSICS | EXPANSIVITY

1.A triangular plate of height 6cm and base length of 12cm is made of metal of linear expansivity 3 x 10^-5 K^-1 as the plate is heated from 15°C to 70°C, the area of one side of the plate will increase to?

A1 = 0.5*12*6 = 36cm^2
Superficial expansivity, B = 2æ
B = 2*3*10^-5
= 6 *10^-5K^-1
∆@= 70 -15 = 55°C
A2=A1(B∆@ + 1)
A2 = 36(6*10^-5*55 + 1)
A2 = 36(0.0033 + 1)
A2 = 36(1.0033)
A2 ~= 36.12cm^2 to 2d.p

horpeyemmi66:
Since PE=KE, then
KE=1/2mv^2=PE=mgh
KE= 65 x10 x 50
KE= 32,500J

you didn't consider the fact that the ball has only traveled for 5s, the height Won't be 50m. Anyway, second half I'd about to begin. See you guys later

horpeyemmi66:
@OGOJNR do refer to mathefaro's solutions (although I am still gonna give out the answers), and mathefaro see OGOJNR's answer to no 1.

You guys are left with question 2, you have successfully dealt with 1,3 and 4.

Expecting it soon...

Let me give you a clue, it is related to the narrow tube system of calculation but you don't invert this tube, which signifies what?

I didn't touch the other question because you said he's gotten it and right now I'm at the viewing center....

horpeyemmi66:
*PHYSICS | GAS LAWS

4. An air bubble at the bottom of a lake 200m deep has a volume of 0.5cm^3. If the bubble rises, calculate the volume just below the surface of the lake, if the atmospheric pressure is 0.76mHg.[Take g=10m/s^2, density of Hg= 1.36 x 10^4Kg/m3 and density of water in the lake =1000kg/m3]

First and foremost, we need to find the height of water,hw that will support 1 atm (0.76mHg).
We know that P = hdg (where d stands for density), therefore,
Pw = Pm (w = water & m = Hg)
hw*1000*10 = 0.76*1.36*10^4*10
hw*10^3 = 1.034*10^4
hw = 1.034*10 = 10.34m

Now to get the required volume of bubble(V2),
P1 (pressure at bottom of lake) = 200 + 10.34 = 210.34m of water
V1 = 0.5cm^3
P2(at the surface) = 10.34m of water
V2 = ?
P1V1 = P2V2
210.34*0.5 = 10.34*V2
V2 = 105.17/10.34
V2 = 10.17cm^3 to 2dp

horpeyemmi66:
*PHYSICS | GAS LAWS

1. An air bubble rises from the bottom to the top of a water dam which is 40m deep. The volume of the bubble just below the surface of the dam is 2.5cm-cube. Find its volume at the bottom of the dam, if the atmospheric pressure is equivalent to 10m of water.

P1(at the surface) = 10m
V1 =2.5cm^3
P2(at the bumbum of the dam) = 10+40 = 50
V2 =?
According to Boyle's law, P1V1=P2V2. Therefore,
10*2.5 = 50*V2
25 = 50V2
V2 = 0.5cm^3

Luukasz:
I Hope the form is not yet Out??

Not out yet. Possibly this month or the next

Luukasz:
U cant be serious.......23,000 Candidates are u sure??

You definitely have not been following updates about UI admission. The information is all over the internet....

horpeyemmi66:
I never intended to still include the sign, but it escaped my mind.

cool

OGOJNR:
since it z a convex mirror v? 1/-10=1/20-1/v...v=6.67 BT hi/ho=v/u...hi/2.5=6.67/20...hi=0.83

exactly bro

horpeyemmi66:
Ok then, perhaps

-1/f= 1/u + 1/v
-1/10= 1/20 + 1/v
-1/10 - 1/20 = 1/v
-2-1/20 = 1/v
v= -20/3

Ih/Oh = Id/Od
Ih/2.5 = -20/3/20
20Ih= 2.5 x -20/3
Ih= -16.67/20
Ih= -0.83cm

yah, but since the -ve sign is only signifying the fact that the image us virtual, you don't need it in the second part if the calculation. So the answer is just 0.83cm, which is apparently a diminished image compared to the object height of 2.5cm. And we know that that convex mirrors will always produce diminished, erect and virtual images....

horpeyemmi66:
@mathefaro here is your answer.

M=Ih/Oh=Id/Od

Ih is missing so

1/f= 1/u + 1/v
1/10= 1/20 + 1/v
1/v = 1/10 - 1/20
1/v= 1/20
v=20cm

therefore

M= Ih/2.5= 20/20
Ih/2.5=1
Ih is therefore 2.5cm

Try again bro

An object of height 2.5cm is placed 20cm from a convex mirror of focal length 10cm. Calculate the height of its image.

NB: Solve carefully

horpeyemmi66:
2. The colour of Methylorange in acidic solution is?

A. Pink

B. Colourless

C. Yellow

D. Red

2. D

Why Methylorange is Red in Acidic medium and Yellow in Alkaline medium.

Actually, you can't actually blame a student who uses New school chemistry by Osei Yaw Ababio if he/she opts for A. Pink. I actually wanted to argue with you on it but after looking up for it online, I realised it could also be red..

Modified

horpeyemmi66:
*CHEMISTRY

1. A acid and its conjugate base differ by what?

A. A Proton

B. An electron

C. A neutron

D. 2 electrons

A. Proton

2. The colour of Methylorange in acidic solution is?

A. Pink

B. Colourless

C. Yellow

D. Red

A. Pink, yellow in an alkaline solution and orange in a neutral solution

3. The oxidation state of H is +1 except in?

A. Peroxides

B. Anhydrides

C. Metallic hydrides

D. Adducts

C. Metallic hydride, where the oxidation state is -1

4. The acid which ants inject into the bodies of their preys or used for defence is which?

A. HCOOH

B. Oxalic acid

C. CH3OHCOOH

D HCOOHOH

A. HCOOH, formic acid/methanoic acid

5. H2SO4 acts on rust as a what?

A. Strong acid

B. Dehydrating agent

C. Reducing agent

D. Oxidizing agent

A. Strong acid, neutralizes the rust(hydrated Fe2O3) which is a base

6. Which of the following indicators is suitable for use in the titration between a Strong base and a weak acid
A. Litmus

B. Any indicator

C. Congo red

D. Phenolphthelein
-

The suitable indicator is phenolphtalein.
MODIFIED. I actually thought I saw strong acid and weak base

horpeyemmi66:
*CHEMISTRY
1. Which of the following ways is not a way of producing an acid

A. Mixing of constituent elements

B. Using a strong acid to displace a weak acid or Volatile acid from its salt

C. Dissolving of acid anhydrides in water

D. Mixing two corrosive bases

Of course, D

2. Hydrogen and helium are employed to do what?

A. Scuba diving

B. As aerodrome beacons

C. To make colourful lights

D. To prevent the oxidation of lamp filaments

Are you sure it's not oxygen and helium? Used by divers...

5. Which of the following dissociates to produce three different kinds of ions in solution

A. Complex salt

B. Acid Salt

C. Basic salt

D. Normal salt

The answer should be a double salt which isn't in the options

10. The basicity of ethanoic acid can be said to be

A. 4

B. 3

C. 2

D. 1

D. 1

initialize:
Instock #3,000

do you have the one for f2 also?