Biology; Chemistry; Physics: Post your doubts here!

[usama321]

No, A should be the answer since BaSO4 is not soluble and hence, the method would NOT work.

awwwwwwwwwwwwww, this is so unfair. Copper would not have reacted either, and they did not mention any heating or other such thing to suggest otherwise

 

[Saad Mughal]

awwwwwwwwwwwwww, this is so unfair. Copper would not have reacted either, and they did not mention any heating or other such thing to suggest otherwise

Actually it would, Copper (II) hydroxide (a base) and Sulphuric Acid would have a neutralization reaction not a displacement reaction.

 

[usama321]

i overlooked this.

 

[Saad Mughal]

i overlooked this.

So did I.

 

[A star]

thankGod you guys made it in practice i made it in my atp paper of cie

 

[usama321]

thankGod you guys made it in practice i made it in my atp paper of cie

 

[ijlalm]

B should be the answer.

Think A is the answer because the barium sulfate would be insoluble and give a white ppt . They are asking that MSO4 is aqueous.

 

[usama321]

Think A is the answer because the barium sulfate would be insoluble and give a white ppt . They are asking that MSO4 is aqueous.

yup A is the answer

 

[TheStallion-Reborn]

Could also anyone can tell me what is a repeat unit in a polymer..??

it is the monomer which gets repeated again and again to form a polymer

 

[TheStallion-Reborn]

can any1 help me with the main required key points of Cathode Ray oscilloscope?

 

[usama321]

can any1 help me with the main required key points of Cathode Ray oscilloscope?

see last page, Saad covered it in detail

 

[Saad Mughal]

can any1 help me with the main required key points of Cathode Ray oscilloscope?

A cathode ray oscilloscope consists of a cathode, a grid (optional), an anode, y-plates, x-plates and a florescent screen.
The cathode is heated (like a filament) and it emits electrons (thermionic emission).
The anode is connected to a large positive potential (hence it is positively charged), it attracts the electrons and accelerates and concentrates them onto a straight beam and travels to the screen.
The y-plates are connected to the voltage (that is applied) (they are responsible for the vertical movements on the CRO) and deflects/moves the electrons accordingly.
The x-plates are connected to the time base (they are responsible for the horizontal movements), they move the electrons left or right.
The florescent screen is a screen made of florescent (it is chosen because it glows and produces a bright spot where the electrons strike them).
The grid, is connected next to the cathode, it has a negative potential connected across it, it deflects the electrons coming from the cathode (and hence, controls the number of electrons hitting the screen). The grid is the brightness control of the CRO.
The whole area inside the CRO is a vacuum (no air), since air molecules would bombard the electrons.
A diagram is attached to help you understand. If you have any queries, just ask.

View attachment 24082

Other than this, you need to know that CRO's are used to display wave forms, measure pd's (by the vertical movement on the screen), measure short intervals of time (used to calculate speed of sound, using concepts of echos).

 

[TheStallion-Reborn]

A cathode ray oscilloscope consists of a cathode, a grid (optional), an anode, y-plates, x-plates and a florescent screen.
The cathode is heated (like a filament) and it emits electrons (thermionic emission).
The anode is connected to a large positive potential (hence it is positively charged), it attracts the electrons and accelerates and concentrates them onto a straight beam and travels to the screen.
The y-plates are connected to the voltage (that is applied) (they are responsible for the vertical movements on the CRO) and deflects/moves the electrons accordingly.
The x-plates are connected to the time base (they are responsible for the horizontal movements), they move the electrons left or right.
The florescent screen is a screen made of florescent (it is chosen because it glows and produces a bright spot where the electrons strike them).
The grid, is connected next to the cathode, it has a negative potential connected across it, it deflects the electrons coming from the cathode (and hence, controls the number of electrons hitting the screen). The grid is the brightness control of the CRO.
The whole area inside the CRO is a vacuum (no air), since air molecules would bombard the electrons.
A diagram is attached to help you understand. If you have any queries, just ask.

View attachment 24082

is this ALL i need to knw about CRO? and what about the cro screen given and we might be asked to provide details like the amout of voltage applied etc etc...

 

[usama321]

is this ALL i need to knw about CRO? and what about the cro screen given and we might be asked to provide details like the amout of voltage applied etc etc...

actually once you have the understanding of it, i think you should do past papers and you will get the practice you need

 

[usama321]

25
Which statement is
not
a reason for the importance of recycling aluminium?
A
Aluminium is a rare metal in the Earth’s crust.
B
The demand for aluminium continues to rise annually.
C
The extraction of aluminium from its ore is expensive.
D
The properties of aluminium make it one of the most useful of all metals

 

[TheStallion-Reborn]

25
Which statement is
not
a reason for the importance of recycling aluminium?
A
Aluminium is a rare metal in the Earth’s crust.
B
The demand for aluminium continues to rise annually.
C
The extraction of aluminium from its ore is expensive.
D
The properties of aluminium make it one of the most useful of all metals

D

 

[Kamihus]

25
Which statement is
not
a reason for the importance of recycling aluminium?
A
Aluminium is a rare metal in the Earth’s crust.
B
The demand for aluminium continues to rise annually.
C
The extraction of aluminium from its ore is expensive.
D
The properties of aluminium make it one of the most useful of all metals

A: it isnt rare

 

[Saad Mughal]

is this ALL i need to knw about CRO? and what about the cro screen given and we might be asked to provide details like the amout of voltage applied etc etc...

It's just like reading a graph, I assume you can do that.
The y-gain and the x-gain will be given (they are the SCALES for the graph).

 

[fatima0000]

what is the necessity of chlorophyll, carbondioxide and light for photosynthesis??

 

[Saad Mughal]

what is the necessity of chlorophyll, carbondioxide and light for photosynthesis??

Chlorophyll is the catalyst for the reaction of creation of glucose. Otherwise, the reaction would be too slow and the plants would die away.
Light (from sun mostly) provides the energy for the reaction of photosynthesis.
Carbon dioxide is an essential part of the photosynthesis process as 6CO2 + 6H2O (from soil) ---> C6H12O6 + 6O2. Without CO2, the process would be incomplete.