| Reverse of the following chemical reaction is not possible: |
| \[Zn(s)+CuS{{O}_{4}}(aq)\to ZnS{{O}_{4}}(aq) + Cu(s)\] |
| Justify this statement with reason. |
| Name the plant hormones responsible for the following functions: |
| (i) growth of the stem |
| (ii) promotes cell division |
| (iii) wilting of leaves |
| (iv) inhibits growth |
| Name the substance oxidised and the substance reduced, and also identify the oxidising agent and reducing agents in the following reaction: |
| (a) \[\mathbf{3Mn}{{\mathbf{O}}_{\mathbf{2}}}\mathbf{+4Al}\to \mathbf{3Mn+2A}{{\mathbf{l}}_{\mathbf{2}}}{{\mathbf{O}}_{\mathbf{3}}}\] |
| (b) \[\mathbf{F}{{\mathbf{e}}_{\mathbf{2}}}{{\mathbf{O}}_{\mathbf{3}}}\mathbf{+3CO}\to \mathbf{2Fe+3C}{{\mathbf{O}}_{\mathbf{2}}}\] |
| (c) \[\mathbf{S}{{\mathbf{O}}_{\mathbf{2}}}\mathbf{+2}{{\mathbf{H}}_{\mathbf{2}}}\mathbf{S}\to \mathbf{3S+2}{{\mathbf{H}}_{\mathbf{2}}}\mathbf{O}\] |
| Differentiate between the following with suitable examples: |
| (i) mineral and ore |
| (ii) corrosion and rancidity |
| (iii) malleability and ductility |
| Draw the pattern of magnetic field lines around a current carrying straight conductor. How does the strength of the magnetic field produced change: |
| (i) with the distance from the conductor? |
| (ii) with an increase in current in a conductor? |
| Find the current drawn from the battery by the network of four resistors shown in the figure. |
 |
| Anita visited her village during summer vacation and saw her grandmother burning firewood to cook food. This caused lots of smoke and resulted in the bad health of Anita's grandmother. Anita suggested some alternatives to her family in the village and offered to help them. Now answer the following questions: |
| (i) List any two alternatives that Anita must have suggested to her grandmother. |
| (ii) How will Anita's grandmother benefit herself and the community by not burning the firewood? Give one reason each. |
| (iii) Which qualities of Anita are reflected in her way of thinking? |
| (a) In column I different methods of extraction are given. Name the methods used for the extraction of metals given in Column II: | |
| Column - I | Column - II |
| (i) Reduction with carbon | Al, Zn, Na, Fe, Mn, Pb |
| (ii) Electrolytic reduction | |
| (iii) Reduction with aluminium | |
| (b) Differentiate between roasting and calcination processes giving one example of each. | |
| (a) Define a universal indicator. Mention its one use. |
| (b) Solution A gives pink colour when a drop of phenolphthalein indicator is added to it. Solution B gives red colour when a drop of methyl orange is added to it. What type of solutions are A and B and which one of the solutions A and B will have a higher pH value? |
| (c) Name one salt whose solution has pH more than 7 and one salt whose solution has pH less than 7. |
| (a) Explain how the separation of oxygenated and deoxygenated blood is useful in humans? |
| (b) Why is double circulation of blood necessary in humans? |
| For the series combination of three resistors establish the relation: |
| \[\mathbf{R = }{{\mathbf{R}}_{\mathbf{1}}}\mathbf{+ }{{\mathbf{R}}_{\mathbf{2}}}\mathbf{+ }{{\mathbf{R}}_{\mathbf{3}}}\] |
| where the symbols have their usual meanings. |
| Calculate the equivalent resistance of the combination of three resistors of \[\mathbf{6}\,\mathbf{\Omega ,}\,\mathbf{9}\,\mathbf{\Omega }\] and \[\mathbf{18}\,\mathbf{\Omega }\] joined in parallel. |
| Study the following current-time graphs from two different sources: |
 |
 |
| (i) Use above graphs to list two differences between the current in the two cases. |
| (ii) Name the type of current in the two cases. |
| (iii) Identify one source each for these currents. |
| (iv) What is meant by the statement that ?the frequency of current in India is 50 Hz?? |
| The pH value of a sample of hydrochloric acid is 2 pH value of this sample when diluted by adding water will be: |
| (a) less than 2 but more than 0 |
| (b) more than 2 but less than 7 |
| (c) more than 7 |
| (d) no change in pH |
| A student added a drop of universal indicator to one ml of the given solution and found that a green colour is produced. pH value of the solution will be in the range of: |
| (a) 0-3 (b) 4-6 |
| (c) 7-9 (d) 10-12 |
| In which form zinc metal is used from laboratory to prepare hydrogen? |
| (a) Rod (b) Powder |
| (c) Filing (d) Granules |
| Aqueous solution of which of the following is colourless? |
| (a) \[FeS{{O}_{4}}\] (b) \[ZnS{{O}_{4}}\] |
| (c) \[A{{l}_{2}}{{(S{{O}_{4}})}_{3}}\] (d) Both (b) and (c) |
| Which of the following solution is coloured? |
| (a) \[ZnS{{O}_{4}}\] (b) \[FeS{{O}_{4}}\] |
| (c) \[A{{l}_{2}}{{(S{{O}_{4}})}_{3}}\] (d) \[N{{a}_{2}}S{{O}_{4}}\] |
| Two resistances are connected in series as shown in the diagram. The potential difference across\[12\,\Omega \]resistor will be: |
 |
| (a) 6 V (b) 2.4 V |
| (c) 2.8 V (d) 12 V |
| Three resistances of \[2\,\Omega ,\,\,3\,\Omega \] and \[5\,\Omega \] are connected in parallel to a 10 V battery of negligible internal resistance. The potential difference across the three resistances will be: |
| (a) 2 V (b) 3 V |
| (c) 5 V (d) 10 V |
| A destarched leaf on a potted plant was covered with black (A), white (B) and transparent (C) strips of paper as shown in the figure. |
 |
| After six hours of exposure to sunlight the leaf was removed from the plant and tested for starch. |
| Which one of the following will be the correct observation? |
| (a) Whole leaf turned blue black |
| (b) Only B and C portions turned blue-black. |
| (c) Only A and B portions remained colourless and the rest of the leaf turned blue-black. |
| (d) A, B and C portions remained colourless and the rest of the leaf turned blue-black. |
| Rina set up the apparatus for demonstrating that \[C{{O}_{2}}\] is released during respiration of germinating seeds. After 2 hours when she observed the setup she did not find the water to rise in the bent tube from the beaker. The reason could be because: |
 |
| (a) the beaker has coloured water. |
| (b) The set-up is air tight. |
| (c) no oxygen is available to seeds for respiration. |
| (d) carbon-dioxide is not being absorbed. |
| While studying the double displacement reaction, the solutions of barium chloride and sodium sulphate are mixed together. |
| (i) What do you observe as soon as the two solutions are mixed together? |
| (ii) What will happen in the above observation made by you after ten minutes? |
| In an experiment, to study the dependence of potential difference (V) on the electric current (I) across a conductor (resistor), if the circuit is on for long time, then-select two correct options from the following: |
| (i) Zero error of an ammeter will be changed |
| (ii) Zero error of a voltmeter will be changed. |
| (iii) Value of a resistance will be changed. |
| (iv) Resistor will be heated. |
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