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Question
Write true or false .
A black residue is formed when sugar is heated .
Options
True
False
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Solution
True
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RELATED QUESTIONS
TRUE \ FALSE
Copper can displace iron from iron sulphate.
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.
Match the column in the following table.
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
Oxygen is a ______ in respiration.
Write the chemical reaction where the following changes are observed.
Physical state is changed
State the main characteristics of chemical reactions. Give at least one example in each case.
Complete and balance the following reaction:
\[\ce{Pb(NO3)2 ->[\Delta]}\]
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
Give a chemical test to distinguish between the following gases.
SO2 and Cl2
What do you observe when CO2 is passed through lime water first and then a little in excess.
Select the correct answer for the following options:
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of water to quicklime.
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
Match the chemical reactions in List I with the appropriate answer in List II.
| List I | List II | ||
| 1. | \[\ce{XY⇌[heat]X + Y}\] | A: | Displacement reaction |
| 2. | \[\ce{XY->X + Y}\] | B: | Double decomposition |
| 3. | \[\ce{X+Y- + A+B^-->X+B- + A+Y-}\] | C: | Endothermic reaction |
| 4. | \[\ce{X + YZ->XZ + Y}\] | D: | Thermal dissociation |
| 5. | \[\ce{X + Y->[heat]XY -\Delta}\] | E: | Decomposition reaction |
Explain the Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
When lithium metal is placed in hydrochloric acid, _______ gas is evolved.
Analogy:
H2O: Water:: NaCl: ______.
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
Photosynthesis is a chemical charge. Justify your answer.
