Q22 of 27 Page 1

When a few drops of phenolphthalein are added to a dilute solution of sodium hydroxide a pink colour is produced. What will be the colour of the final mixture when an excess of HCl is added to it? (justify your answer)

OR


Arrange the metals iron, magnesium, zinc and copper in the increasing order of their reactivity. What will be the two observations made by the student when iron filings are added to the copper sulphate solution?

The phenolphthalein is an artificial indicator which turns pink when reacting with base and does not react with acid.

When an excess of HCl is added to the mixture, the phenolphthalein solution turns colourless.


OR


The activity series of metals is as follows:



So now as per the above activity series of metals, the increasing order of reactivity is as follows:


Copper<Iron<Zinc<Magnesium


In terms of reactivity of iron and copper, iron being more reactive than copper because displaces the copper from its sulphate solution. The reaction is as follows:


Fe + CuSO4→ FeSO4 + Cu


More from this chapter

All 27 →
20

(a)What is meant by the term ‘power of accommodation’? Name the component of the eye that is responsible for the power of accommodation.

b. A student sitting at the back bench in a class has difficulty in reading. What could be his defect of vision? Draw ray diagrams to illustrate the image formation of the blackboard when he is seated at the (i) back seat (ii) front seat. State two possible causes of this defect. Explain the method of correcting this defect with the help of a ray diagram.

 21

(i) With the help of an activity, explain the method of inducing an electric current in a coil with a moving magnet — State the rule used to find the direction of electric current thus generated in the coil.

(ii) Two circular coils-1 and coil-2 are kept close to each other as shown in the diagram.Coil-1 is connected to a battery and key and coil-2with a galvanometer. State your observation in the galvanometer:



a) When key k closed; (b) when key k is opened; Give a reason for your observations.


OR


Name a device which converts mechanical energy into electrical energy. Explain the underlying principle and working of this device with the help of a labelled diagram.

 23

From an experiment to study the properties of acetic acid. Answer the following questions:

a) Name the substances which on an addition to acetic acid produce carbon dioxide gas. Give relevant chemical equation for the above?


b) How is CO2 gas tested in the laboratory?

 24

When observed under high power of the microscope, ‘chain of buds’ is visible in the microscopic view. In which organism can it be observed? Explain the process.

OR


In the experimental set up on ‘CO2 is released during respiration,’ if one forgets to keep the vial with KOH in the conical flask, how will the result vary? Give details.