Physics, Chemistry and Biology: Post your doubts here!

[Starry4]

Assalam-o-Alaikum.
Post your Physics, Chemistry and Biology doubts in here and members, along with me will try their best to help you out.

I'm struggling with Physics Olevel June 2011 Paper 31, I mean seriously the 2011 students must have had a tough year

 

[shoaib672002]

Plz solve all and with diagrams

 

[dubi2pro]

the 24th one.

How is it 3.0 MOL/DM^3?

 

[Ironheart]

How do i separate hexane from a mixture of hexane and octane?

 

[Awesome12]

How do i separate hexane from a mixture of hexane and octane?

Octane has a higher boiling point than hexane. So you could separate them by fractional distillation

 

[shoaib672002]

Plz solve all and with diagrams

Awesome12

 

[dubi2pro]

the 24th one please why and how is the answer 3.0 mol/dm??

 

[Awesome12]

the 24th one please why and how is the answer 3.0 mol/dm??

Take the readings for the max temp
Moles of HCl = 2.0 * (3/1000)
=0.06

Moles of HCl = Moles of NaOH
0.06 = 0.06

0.06 = Conc. * (20/1000)
Conc. = 3.0 mol/dm^3

 

[Phoenix Blood]

???

 

[Awesome12]

???

A body is stationary or travelling with constant speed only when the forces acting on it are equal

 

[Phoenix Blood]

What sort of soluble substances?

 

[Phoenix Blood]

What justifies the answer? :/

 

[shoaib672002]

dude from which past papers

2013 may june

 

[Awesome12]

What sort of soluble substances?

Pure water is tasteless. So in order to retain the taste, minerals are added

 

[Awesome12]

What justifies the answer? :/

The answer is D
Akalis liberate ammonia when they react with Ammonium Salts
Acids turn litmus red

 

[princess sofia]

cn any1 plz answer thx
part(ii)

 

[Awesome12]

cn any1 plz answer thx
part(ii)View attachment 39303

lets assume the ball has a mass of 3.0 kg
Its Ep = mgh
Ep = 3.0 (10) (4.0)
Ep =120 J

22% of energy is lost
thus, the ball now has: 120*22 /100
= 120-26.4
=93.6 J

The mass and g remain constant

93.6 = 3.0 * 10 * h
Find h

 

[Mavilda Bucket]

why detergents need to be biodegradable and why dont they form a scum????

 

[mushiii]

hello, can someone help me in chemisty paper 3 october november 2007 Question 6 iv

 

[mushiii]

i checked the mark scheme and it says to plot points