Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then a small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured

crystals got separated (step II). Step I and step II are:

physical and chemical changes respectively.

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chemical and physical changes respectively.

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both physical change.

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both chemical change.

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Solution

The correct option is C both physical change.
Step I: Physical change: Only dissolution of copper sulphate powder occurs in the presence of heat and sulphuric acid, but no reaction takes place, nor any new substance is formed but a change of state.

Step II: On cooling this hot solution, crystals of copper sulphate gets separated out, which is a physical change as copper sulphate is obtained again .

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Similar questions

Q. Two drops of dilute sulphuric acid were added to

1 g

of copper sulphate powder and then a small amount of hot water was added to dissolve it (step

I

). On cooling, beautiful blue-coloured crystals got separated (step

I I

). Step

I

and step

I I

are

Question 10

Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and step II are:
(a) physical and chemical changes respectively
(b) chemical and physical changes respectively
(c) both physical change
(d) both chemical change

What would you observe in the following cases?
(i) Sulphur trioxide is dissolved in water on a large scale.
(ii) Concentrated sulphuric acid is added to equal volumes of cold water.
(iii) 100 ml of 98% sulphuric acid is kept open.
(iv) Hot concentrated sulphuric acid is added to sodium chloride crystals.
(v) Dilute sulphuric acid is added to ferrous sulphate solution.

Q. The preparation of lead sulphate from lead carbonate is a two-step process (lead sulphate cannot be prepared by adding dilute sulphuric acid to lead carbonate.)
(i) What is the first step that is required to prepare lead sulphate from lead carbonate?
(ii) Write the equation for the reaction that will take place when this first step is carried out.
(iii) Why is the direct addition of dilute sulphuric acid to lead carbonate an impractical method of preparing lead sulphate?

Write down the changes that will be seen in each instance and explain the reason behind it.

(a) 50ml water is added to 50ml solution of copper sulphate.

(b) Two drops of the indicator phenlphthalein were added to 10ml solution of sodium hydroxide.

(d) A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.

(e) Magnesium oxide was added to dilute HCl and magnesium oxide was a added to dilute NaOH.

(f) Zinc oxide was added to dilute HCl and zinc oxide was added to dilute NaOH.

(g) Dilute HCl was added to limestone.

(h) Pieces of blue vitriol were heated in a test tube. On cooling, water was added to it.

(i) Dilute H 2 SO 4 was taken in an electrolytic cell and electric current was passed through it.

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