Biology; Chemistry; Physics: Post your doubts here!

[nightmaressana]

my teacher says that fig1.a produces more current can u explain why???

what i think is that fig 1.b will produce more current. because the more magnetic flied lines the coil cuts the stronger the current. Also, in fig 1.a the magnetic field lines would be attracted by the opp poles, thus, less magnetic field lines will be able to cut coil, thus less current would be produced.
i hope that my answers correct

 

[tdk]

How can we separate Potassium Chloride and Sodium Chloride from the solution of the two?

 

[scouserlfc]

I dont think u will get a question like this ! Its way too advanced too seperate two ionic and soluble salts with very less differences in them !

 

[..sacrifice4Revenge..]

Chemistry help...

fill in the blanks...
1) the acidic soils can be treated with______ which causes _____ to restore plant growth.
2) When water is added to MgNO3 _______ and _____ are formed.The equation for this reaction is ________.
my answer for 2(HNO3) ( MgO) is it correct if yes plz give eq.

Q. following data shows decomposition of H2O2 at different condition.
1) 50cm3 H2O2 + 1.0G OF CuO
2) 25cm3 H2O2 + 25cm3 of H2O + 1.0g of CuO
3) 50 cm3 of H2O2 only

Explain in detail which reaction will be slowest and fastest? Why? Compare the reaction rate under 3 given conditions.

 

[snowbrood]

Chemistry help...

fill in the blanks...
1) the acidic soils can be treated with______ which causes _____ to restore plant growth.
2) When water is added to MgNO3 _______ and _____ are formed.The equation for this reaction is ________.
my answer for 2(HNO3) ( MgO) is it correct if yes plz give eq.

Q. following data shows decomposition of H2O2 at different condition.
1) 50cm3 H2O2 + 1.0G OF CuO
2) 25cm3 H2O2 + 25cm3 of H2O + 1.0g of CuO
3) 50 cm3 of H2O2 only

Explain in detail which reaction will be slowest and fastest? Why? Compare the reaction rate under 3 given conditions.

1.can be treated by calcium oxide calcium carbonate or calcium hydroxide... magnesium hydroxide could also be used it causes neutralization these compounds reacts with the acidity in the soil
2.Mg(NO3)2 + 4H2O -----> Mg(OH)2 + 2NH3 + 4O2.
at room temperature hydrogen peroxide decompose very slowly the presence of catalyst such as CuO increases the rate of reaction so 1 is the fastest reaction while the 3 is the slowest... in reaction no 2 water dilutes hydrogen peroxide decreasing its concentration thus fewer molecules would be there in a dilute solution to react with CuO this would definently decrease the rate of reaction

 

[snowbrood]

hit like if i was able to answer ur question

 

[tania]

please help me with moments and electronics especially nand latch nd other bla bla stuff.........

 

[snowbrood]

why bell works on both dc and ac current

 

[Hateefa]

If i want to be a doctor. i must do physics? or can i do only biology and chemistry?

 

[snowbrood]

If i want to be a doctor. i must do physics? or can i do only biology and chemistry?

well in o level u have to take physics whether u be a doc or engineer

 

[nightmaressana]

guys are there any notes available for the chapter radioactivity and electronics according to syllabus?

 

[..sacrifice4Revenge..]

2) When water is added to MgNO3 _______ and _____ are formed.The equation for this reaction is ________.
plz give answer and explain...


also:
Q) concentration of dilute H2SO4 in lab is often 2mol/dm3
What is the mass of H2SO4 in 25.0cm3 of this acid.

 

[..sacrifice4Revenge..]

Q. following data shows decomposition of H2O2 at different condition.
1) 50cm3 H2O2 + 1.0G OF CuO
2) 25cm3 H2O2 + 25cm3 of H2O + 1.0g of CuO
3) 50 cm3 of H2O2 only

Explain in detail which reaction will be slowest and fastest? Why? Compare the reaction rate under 3 given conditions.

Plz answer wid the 3 CONDITIONS IN mind ..
thnx

 

[scouserlfc]

2) When water is added to MgNO3 ._Mg(OH)2 _____ and __HNO3___ are formed.The equation for this reaction is ___Mg(NO3)2 + 2H2O ---> Mg(OH)2 + 2HNO3 _____.
plz give answer and explain...

simple break the ions and form the ions again but join differently this time ! ! ! Mg(NO)3 is a salt so on breaking with water it should reveal its base and acid which formed it !


also:
Q) concentration of dilute H2SO4 in lab is often 2mol/dm3
What is the mass of H2SO4 in 25.0cm3 of this acid.

2*(25*1000)
=0.05 moles

H2SO4 M.mass = 98
0.05*98= 4.9g !
i get what this question was so ill check if im wrong and correct it but if my answer is wrong then let me know ! !

 

[scouserlfc]

Q. following data shows decomposition of H2O2 at different condition.
1) 50cm3 H2O2 + 1.0G OF CuO
2) 25cm3 H2O2 + 25cm3 of H2O + 1.0g of CuO
3) 50 cm3 of H2O2 only

Explain in detail which reaction will be slowest and fastest? Why? Compare the reaction rate under 3 given conditions.

Plz answer wid the 3 CONDITIONS IN mind ..
thnx

Option 2 will be the fastest ! ! !! ! ! !

This is because by dissolving in water in 2 it increases the surface area of H2O2 available for decomposition so more molecules can get the heat and decompose !
Another thing is that using less H2O2 again speeds up the rate of reaction as it will take less time for breaking down less particles of H2O2 if they are less and they have increased surface area ! The presence of catalyst further makes the rate of reaction fast as it lowers the activation energy required by the H2O2 to reach before it can form its products remember catalyst is also present in 1 but in two as other conditions increase the rate of reaction this further increases the rate ! !

 

[scouserlfc]

why bell works on both dc and ac current

I think the bell works on ac as well as dc as the bell doesnt utilise the electromagentic induction effect and therefore it works perfectly !
think abt it the bell only works when the switch is opened the current flows and the electromagnet becomes a magnet and attracts the soft iron bar having the gong and u have to leave the switch for the gong to come back to its original position but with ac. supply reversal of poles doesnt result in any repulsion but attraction only as the soft iron is not a magnet !
but ac is not ideal for the bell ! ! ! !

 

[scouserlfc]

please help me with moments and electronics especially nand latch nd other bla bla stuff.........

Where is the help wanted like the basic stuff or u have problem understanding the concepts !

 

[snowbrood]

Option 2 will be the fastest ! ! !! ! ! !

This is because by dissolving in water in 2 it increases the surface area of H2O2 available for decomposition so more molecules can get the heat and decompose !
Another thing is that using less H2O2 again speeds up the rate of reaction as it will take less time for breaking down less particles of H2O2 if they are less and they have increased surface area ! The presence of catalyst further makes the rate of reaction fast as it lowers the activation energy required by the H2O2 to reach before it can form its products remember catalyst is also present in 1 but in two as other conditions increase the rate of reaction this further increases the rate ! !

hydrogen peroxide is a liquid how could water actually increase its surface area it would decrease the concentration of hydrogen peroxide in the solution so it wont be the fastest reaction

 

[snowbrood]

I think the bell works on ac as well as dc as the bell doesnt utilise the electromagentic induction effect and therefore it works perfectly !
think abt it the bell only works when the switch is opened the current flows and the electromagnet becomes a magnet and attracts the soft iron bar having the gong and u have to leave the switch for the gong to come back to its original position but with ac. supply reversal of poles doesnt result in any repulsion but attraction only as the soft iron is not a magnet !
but ac is not ideal for the bell ! ! ! !

yea u are right abt this one well the bell would now make a buzzing sound as the attraction goes to zero at each polarity reversal

 

[scouserlfc]

hydrogen peroxide is a liquid how could water actually increase its surface area it would decrease the concentration of hydrogen peroxide in the solution so it wont be the fastest reaction

Yeah but its not mentioned if its in liquid or solid state so i did it on the basis of a solid ! ! But by assuming room temp then it should be reaction 1 ! that would be fastest !