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Write one equation for decomposition reactions where energy is supplied in the form of light.
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Write one equation for decomposition reactions where energy is supplied in the form of electricity.
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A solution of a substance ‘X’ is used for whitewashing.
- Name the substance ‘X’ and write its formula.
- Write the reaction of the substance ‘X’ named in the above formula with water.
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\[\ce{Fe2O3 + 2Al -> Al2O3 + 2Fe}\]
The above reaction is an example of a ______.
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What happens when dilute hydrochloric acid is added to iron fillings? Choose the correct answer.
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Write the balanced chemical equation for the following and identify the type of reaction.
\[\ce{Magnesium(s) + Hydrochloric acid(aq) -> Magnesium chloride(aq) + Hydrogen(g)}\]
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In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
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On what factors does the resistance of a conductor depend?
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Use the data in the Table given below to answer the following –
Which among iron and mercury is a better conductor?
Table give below Electrical resistivity of some substances at 20°C
| Electrical resistivity of some substances at 20°C | ||
| − | Material | Resistivity (Ω m) |
| Conductors |
Silver | 1.60 × 10−8 |
| Copper | 1.62 × 10−8 | |
| Aluminium | 2.63 × 10−8 | |
| Tungsten | 5.20 × 10−8 | |
| Nickel | 6.84 × 10−8 | |
| Iron | 10.0 × 10−8 | |
| Chromium | 12.9 × 10−8 | |
| Mercury | 94.0 × 10−8 | |
| Manganese | 1.84 × 10−6 | |
| Alloys |
Constantan (alloy of Cu and Ni) |
49 × 10−6 |
| Manganin (alloy of Cu, Mn and Ni) |
44 × 10−6 | |
| Nichrome (alloy of Ni, Cr, Mn and Fe) |
100 × 10−6 | |
| Insulators | Glass | 1010 − 1014 |
| Hard rubber | 1013 − 1016 | |
| Ebonite | 1015 − 1017 | |
| Diamond | 1012 − 1013 | |
| Paper (dry) | 1012 | |
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What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?
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Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:
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A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10−8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?
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Why are copper and aluminium wires usually employed for electricity transmission?
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Write the molecular formula of the 2nd and 3rd member of the homologous series whose first member is ethene.
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List the factors on which the resistance of a conductor in the shape of a wire depends.
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Why are alloys commonly used in electrical heating devices? Give reason.
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Fill in the following blanks with suitable words:
Copper is a good .......... Plastic is an ..........
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What is meant by conductors and insulators? Give two examples of conductors and two of insulators.
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Which of the following are conductors and which are insulators?
Sulphur, Silver, Copper, Cotton, Aluminium, Air, Nichrome, Graphite, Paper, porcelain, Mercury, Mica, Bakelite, Polythene, Manganin.
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What is the general name of the substances having infinitely high electrical resistance?
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