Biology; Chemistry; Physics: Post your doubts here!

[a.abid]

hey dont worry
check this out and youll be fine
http://www.chemguide.co.uk/inorganic/group1/reacth2o.html

now that was quite helpful

 

[Spidey21]

Of course I got it .. then you deny ur frst statement.. coz it contradicts

here ya go
http://www.chemguide.co.uk/inorganic/group1/reacth2o.html
hope it helps

 

[MustafaMotani]

here ya go
http://www.chemguide.co.uk/inorganic/group1/reacth2o.html
hope it helps

Thank you Spidey

 

[a.abid]

here ya go
http://www.chemguide.co.uk/inorganic/group1/reacth2o.html
hope it helps

oh thankyou I always forget to say that....

 

[Spidey21]

oh thankyou I always forget to say that....

no need

 

[Spidey21]

Thank you Spidey

no broblem dude..

 

[paradoX error]

Green ppt of iron(II) hydroxide will be seen.
there will also be a white ppt of calcium hydroxide but it will not be seen due to the green one.

CA is more reactive than iron so how come iron displace calcium from calcium hydroxide and form fe(oh)2 ?
:S

 

[Spidey21]

CA is more reactive than iron so how come iron displace calcium from calcium hydroxide and form fe(oh)2 ?
:S

where did that happen???
give that guy a noble prize who did it..

 

[Fallen316]

CA is more reactive than iron so how come iron displace calcium from calcium hydroxide and form fe(oh)2 ?
:S

it doesnot displace it . they both are in the solution.
its just that the green color is only visible. but calcium hydroxide ( which is white ) is also present.

 

[paradoX error]

where did that happen???
give that guy a noble prize who did it..

tht cubby double chinned nerd

 

[MustafaMotani]

tht cubby double chinned man

xD

 

[paradoX error]

it doesnot displace it . they both are in the solution.
its just that the green color is only visible. but calcium hydroxide ( which is white ) is also present.

LOL seriously :O ? Chemistry uffffffffffff

 

[a.abid]

tht cubby double chinned man

LOL. I guess Fallen316 wrote it very clearly that CaOh will be present.....I guess u took the statement wrong

 

[daredevil]

continuing my post above and posting more ATP related questions .... like it if u want to




Q50: WHAT IS AN OSCILLATION?
Ans: The process of the bob swinging back and forth steadily and coming back to its original position.
Q52: HOW WILL YOU NEASURE THE LENGTH OF A PENDULUM?
Ans: Using a meter rule and set-square. Place the meter rule close to the thread and note the length of the upper and lower ends of the pendulum (l1 and l2). The length l is calculated by l2 - l1.
Q53: WHAT IS THE USE OF SET SQUARE?
Ans: They are used to allign the ruler to get the correct reading. They help to avoid parallax errors.
Q55: WHAT IS A MEASUREMENT?
Ans: The size, amount of degree of a physical quantity.
Q56/57: What is an accurate/precise reading?
Ans: Accuracy - the measure of how close you are to the true answer.
Precision - the measure of how closely all your individual measurement match each other.
Q58/59/61: Define responsiveness, range and sensitivity of a thermometer.
Ans: Range - The minimum and maximum temperatures that the thermometer can measure.
Sensitivity - It is the length of increase of the liquid per degree rise in temperature.
Responsiveness - How quickly the thermometer can register a change in temperature.
Q60/62: How can we increase the responsiveness, range and sensitivity of the thermometer?
Ans:
To increase range:
(a) make the thermometer stem longer
(b) make the bore(capillary) bigger
(c) use a liquid with a lower expansivity
To increase sensitivity:
(a) make the bore smaller
(b) use a bigger bulb
(c) use a liquid with a higher expansivity
To increase responsiveness:
(a) use a thin glass bulb
(b) use a liquid that conducts heat better
　
Q63: WHY THE BORE OF CAPILLARY TUBE IS UNIFORM?
Ans: This improves the thermometer's sensitivity (by giving a large change in length of the mercury thread for a small change in temperature).
Q64: WHY THE WALLS OF LONG TUBE ABOVE THE BULB ARE MADE THICK?
Ans: Acts as a magnifying glass to easily read the mercury thread in the stem.
Q65: WHAT IS THE ADVANTAGE OF SMALL SIZE OF THERMOMETER?
Ans: It makes it cheap to produce, portable, etc.
Q66: WHY THE MERCURY IS CONTAINED IN A THIN-WALL GLASS BULB?
Ans: This allows for rapid conduction of heat through the thin glass wall to the mercury contained in the bulb.
Q67: WHAT IS THE PUPOSE OF CONSTRICTION IN THE CLINICAL THERMOMETER?
Ans: The constriction prevents mercury from flowing back into the bulb.
Q68: WHAT DOES THE STATEMENT MEAN, THAT THE SCALE OF THERMOMETER IS LINEAR?
Ans: It is the uniform expansion of liquid to temperature.
Q69: WHY THE CROSS-SECTION OF THE STEM OF THERMOMETER IS PEAR-SHAPED?
Ans: This acts as a magnifying glass in one direction for easy reading of the mercury thread.

Q. What factors to consider before measuring something?
Ans: The magnitude should not exceed the limit of the instrument, and the instrument must be sensitive enough to detect a meaningful measurement.
Q. When iron fillings are used, why must the current be large?
Ans: So that the field is stronger and hence the field can be detected.
Q. Why must smaller fillings be used?
Ans: So that the weaker magnetic fields are also shown.
Q. Why must the oscillations be counted from center of swing?
Ans: The chain is moving the fastest at the center of swing.
Q. Suggest a suitable number of oscillations, with reason.
Ans: 20. The time for one oscillation is too short to obtain an accurate reading and so 20 oscillations are timed instead.
Q. Why is the reading in a pendulum repeated?
Ans: This will help ensure a more accurate average value for one oscillation (T).
Q. Why is oil stirred during heating?
Ans: To give uniform heating to the mixture.
Q. Why is the oil heated gently?
Ans: So that an equal change in the temperature will result in a small change of temperature in the oil.

 

[Spidey21]

tht cubby double chinned nerd

oh really?? -_-

 

[paradoX error]

LOL. I guess Fallen316 wrote it very clearly that CaOh will be present.....I guess u took the statement wrong

achaaww seriously ? ! tou phir fe(oh)2 kaisay form hua doesnt matter thora sa ya bohat sara bana kaisay thts the big deal . btter understand my argument 2 :roflol:

 

[Spidey21]

achaaww seriously ? ! tou phir fe(oh)2 kaisay form hua doesnt matter thora sa ya bohat sara bana kaisay thts the big deal . btter understand my argument 2 :roflol:

share the basic question again...

 

[a.abid]

achaaww seriously ? ! tou phir fe(oh)2 kaisay form hua doesnt matter thora sa ya bohat sara bana kaisay thts the big deal . btter understand my argument 2 :roflol:

hmm welll u have a point there...can u post the question again?

 

[paradoX error]

Chemistry
June 2009 paper 2
A6 d)

 

[daredevil]

where did that happen???
give that guy a noble prize who did it..

its not a noble prize its a NOBEL prize