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प्रश्न
Grills of doors and windows are always painted before they are used.
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उत्तर
- Usually, grills of doors and windows are made of iron.
- Iron objects get rusted on exposure to moist air.
- Since air always contains moisture, iron grills get rusted.
- Painting iron objects prevents rusting, hence iron grills of doors and windows are painted before they are used.
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संबंधित प्रश्न
Write the balanced chemical equation for the following reaction.
\[\ce{Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride}\]
Write the balanced chemical equation for the following reaction.
\[\ce{Aluminium + Copper chloride -> Aluminium chloride + Copper}\]
Write the balanced chemical equation for the following reaction.
\[\ce{Zinc + Silver nitrate -> Zinc nitrate + Silver}\]
State whether the following statement is true or false:
A chemical equation can be balanced easily by altering the formula of a reactant or product.
How will you indicate the following effect in a chemical equation?
A solution made in water.
Complete and balance the following equation:
\[\ce{NaOH + {..........} -> Na2SO4 + H2O}\]
Write a complete balanced equation for the following reaction:
\[\ce{Sulphur dioxide (gas) + Oxygen (gas) -> Sulphur trioxide (gas)}\]
Rewrite the following information in the form of a balanced chemical equation:
Magnesium burns in carbon dioxide to form magnesium oxide and carbon.
When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
- What could be solid X? Write its chemical formula.
- What could be product Y? Write its chemical formula.
- What is the common name of the solution of Y which is used for testing carbon dioxide gas?
- Write chemical equation of the reaction which takes place on adding water to solid X.
- Which characteristic of chemical reactions is illustrated by this example?
A white precipitate will be formed if we add common salt solution to ______.
Name the type of chemical reaction shown by the following equation:
2Mg+ O2 → 2MgO
Why do we need to balance chemical equations?
Balance the following chemical equation :
FeS + HCl → FeCl2 + H2S
Complete the following equation:
CH2 + H5OH `("Hot Conc." H_2SO_4)/`>
Complete the following equation:
CH3COOH + NaOH →
To determine the percentage of water absorbed by raisins, raisins are soaked in water for:
Balance the following equation:
PbS + O2 → PbO + SO2
Balance the following equation:
\[\ce{S + HNO3 -> H2SO4 + NO2 + H2O}\]
Balance the following equation:
Pb3O4 + HCl → PbCl2 + H2O + Cl2
Balance the following equation:
NaHCO3 → Na2CO3 + H2O + CO2
Balance the following equation:
HNO3 + H2S → NO2 + H2O + S
Write the balanced chemical equation of the following reaction.
potassium bicarbonate + sulphuric acid → potassium sulphate + carbon dioxide + water
Write the balanced chemical equation of the following reaction.
zinc sulphide + oxygen → zinc oxide + sulphur dioxide
Write the balanced chemical equation of the following reaction.
aluminium sulphate + sodium hydroxide → sodium sulphate + sodium meta aluminate + water.
(a) Give only one suitable chemical test to identify the following gases.
- Ammonia
- Sulphur dioxide
- Hydrogen Chloride
- Chlorine
- Carbon Dioxide
- Oxygen
- Hydrogen
(b) Select a basic gas mentioned in Q.1 (a). How is the basic nature suspected?
(c)Select acidic gases from the gases mentioned in Q.1 (a). How is the acidic nature suspected?
(d) State the gas responsible for bleaching action.
(e)Which gas turn blue cobalt chloride paper light pink?
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – copper carbonate.
Give one example in the case where supplying energy [given below] is necessary for a chemical reaction.
Light energy
Write word equation for the following chemical reaction given below. Also state the observation seen in the case.
\[\ce{Na2SO3 + 2HCl ->[\triangle] 2NaCl + H2O + SO2}\]
Balance the following simple equation:
C + O2 → CO
Balance the following simple equation:
SO2 + O2 ⇌ SO3
Balance the following simple equation:
Fe + H2O ⇌ Fe3O4 + H2
Balance the following simple equation:
H2 + O2 → H2O
Write a balanced equation for the following word equation:
Calcium hydroxide + Ammonium chloride → Calcium chloride + Water + Ammonia
Fill in the blank with the correct word from the options given below:
A chemical equation is a shorthand form for a _______ change.
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
CaC2 + N2 → 2CaCN2 + C
Reema took 5ml of Lead Nitrate solution in a beaker and added approximately 4ml of Potassium Iodide solution to it. What would she observe?
Which of the following statements about the given reaction are correct?
`3"Fe"("s") + 4"H"_2"O"("g") -> "Fe"_3"O"_4("s") + 4"H"_2("g")`
- Iron metal is getting oxidised
- Water is getting reduced
- Water is acting as reducing agent
- Water is acting as oxidising agent
Complete the following blank in the equation as indicated.
\[\ce{CaH2_{(s)} + 2H2O_{( aq)}-> Ca(OH)2_{(s)} + 2H2_{(g)}}\]
Molecules: 6.02 × 1023 + ______ `→` ______ + ______
