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Calculate the focal length of a corrective lens having power +2.5 D.
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The atomic masses of three elements A, B and C having similar chemical properties are 7, 23 and 39, respectively.
- Calculate the average atomic mass of elements A and C.
- Compare the average atomic mass with atomic mass of B.
- What could the elements A, B and C be?
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Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
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Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
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Differentiate between Normal elements and Transition elements.
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Write the chemical formula of rust.
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Which one of the following does not increase while moving down the group of the periodic table?
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Give scientific reason.
It is reccommended to use air tight container for storing oil for long time.
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Identify from the reaction the reactants that undergo oxidation and reduction.
Fe + S → FeS
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Identify from the following reaction the reactants that undergo oxidation and reduction.
\[\ce{2Ag2O → 4 Ag + O2 \uparrow}\]
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Identify from the reaction the reactants that undergo oxidation and reduction.
2Mg + O2 → 2MgO
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Identify from the reaction the reactants that undergo oxidation and reduction.
\[\ce{NiO + H2 -> Ni + H2O}\]
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Solve the following example.
Doctor has prescribed a lens having power +1.5 D. What will be the focal length of the lens? What is the type of the lens and what must be the defect of vision?
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Draw a neat labelled diagram.
Magnetic separation method.
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Draw a neat labelled diagram.
Froth floatation method.
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Draw a neat labelled diagram.
Electrolytic reduction of alumina.
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Draw a neat labelled diagram.
Hydraulic separation method.
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Atomic number of metal ‚A‛ is 11, while atomic number of metal ‚B‛ is 20. Which of them will be more reactive? Write the chemical reaction of dilute HCl with metal ‚A‛.
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