In chemistry laboratory, the students added zinc granules in a conical flask and all of them poured a few drops of dilute sulphuric acid into the flask and made the following. observations.
(1) Bubbles of gas are found to rise briskly from the surface of zinc metal.
(11) There is a change in the temperature.
(III) A yellow coloured solution is formed.
(IV) The colour of the gas formed is brown.
Which of the above observations are correct?
(a) Only (1)
(b) Only (11)
(c) Bath (III)
and (IV)
(d) Both (1) and (II)
2. The green colour of metal solt ‘A’ first changes to white solid ‘B’ on heating. On
Metal Salt ‘A’
White Solid ‘B’
further heating, white solid ‘B’ turns into a brownish black substance ‘C’. Which of the following option gives the correct information about the substances and the type of reaction involved?
A pair of tongs
Balling tube
Burner
Heating of Lead Nitrate and Emission of Nitrogen Dioxide
Brownish Black Substance ‘C’
Type of Reaction
(a) Pb(NO3)2.7H2O
Pb(NO3)2
Thermal Decomposition
(b) CuSO4.5H₂O
CuSO
CuSO
Thermal Decomposition
(c) FeSO4.7H2O
FeSO4
Fe2O
Thermal Decomposition
(d) FeSO4.5H₂O
FeSO
FeO
100
Endothermic
3. A balanced chemical equation tells us that the total mass of elements present in the products of a chemical reaction is equal to the total mass of the elements present in the reactants. But it does not provide us information about some facts and then the reaction is made informative by adding additional information. Select the statement that does not make the chemical reaction more informative.
(a) Physical state of reactants and products are written along with them.
High difficulty Os, adapted from well-known reference books.
(b) The reaction conditions under which the reaction takes place are written.
(c) To balance a chemical reaction, coefficient is always written infront of the formula.
(d) Heat changes accompanying the chemical reaction are written.
4. On heating a blue-coloured powder of copper (II) nitrate in a boiling tube, a black substance X, oxygen gas and a brown gas Y was formed. Select the option which identifies the products correctly:
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