Q8 of 28 Page 187

Take copper nitrate in a test tube and heat it over the flame.

i) What is the colour of cupric nitrate?


ii) What do you observe?


iii) Name the type of reaction that takes place.


iv) Write the balanced equation.

(i) The colour of cupric nitrate is deep blue green colour.


(ii) When copper nitrate is heated in a test tube it loses the water molecule or the water of crystallisation present in it and then when it is further heated it decomposes to give Copper oxide, nitrogen dioxide and oxygen. It would be observed during the reaction that a reddish brown colour gas(nitrogen dioxide) is evolved.


(iii) The above reaction is a type of decomposition reaction.


(iv) The balanced equation is : -


2Cu(NO3)2 2CuO + 4NO2↑ + O2↑


More from this chapter

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6

Two acids ‘A’ and ‘B’ were kept in beakers. Acid ‘A’ undergoes partial dissociation in water, whereas acid ‘B’ undergoes complete dissociation in water.

i) Of the two acids ‘A’ and ‘B’ , which is weak acid and which is strong acid?


ii) What is a weak acid?


iii) What is a strong acid?


iv) Give one example each.

 7

Observe the given chemical change and answer the following:


i) Identify ‘A’ and ‘B’.


ii) Write the commercial name of calcium hydroxide.


iii) Identify products ‘C’ and 'D' , when HCl is allowed to react with calcium oxide.


iv) Say whether calcium oxide is acidic or basic.

 9

Identify the wrong statements and correct them.

i) Sodium benzoate is used in food preservative.


ii) Nitric acid is not used as fertilizer in agriculture.


iii) Sulphuric acid is called the king of chemicals.


iv) The PH of acid is greater than 7.


v) Acetic acid is used in aerated drinks.

 10

Redox reactions are reactions during which electron transfer takes place. Here

magnesium atom transfers two electrons one each to the two chlorine atoms.


i) What are the products of this reaction?


ii) Write the balanced equation for the complete reaction.


iii) Which element is being oxidized?


iv) Which element is being reduced?


v) Write the reduction part of the reaction.