• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Biology; Chemistry; Physics: Post your doubts here!

paradoX error

paradoX error

Messages
971
Reaction score
2,693
Points
253
Fallen316 said:
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.
Click to expand...
CA is more reactive than iron so how come iron displace calcium from calcium hydroxide and form fe(oh)2 ?
:S
 
Fallen316

Fallen316

Messages
1,035
Reaction score
539
Points
123
paradoX error said:
CA is more reactive than iron so how come iron displace calcium from calcium hydroxide and form fe(oh)2 ?
:S
Click to expand...
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.
 
daredevil

daredevil

Messages
1,394
Reaction score
1,377
Points
173
continuing my post above and posting more ATP related questions .... like it if u want to (y) :p




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.
 
You must log in or register to reply here.
Top