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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
Balance the chemical equation.
\[\ce{HNO3 +Ca(OH)2 -> Ca(NO3)2 + H2O}\]
Translate the following statement into chemical equation and then balance the equation:
Barium chloride reacts with zinc sulphate to give zinc chloride and barium sulphate.
Complete and balance the following equation:
NaOH + ............ 
Na2 SO4 + H2O
What is a chemical equation? Explain with the help of an example.
What are the various ways in which a chemical equation can be made more informative? Give examples to illustrate your answer.
Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
Balance the following chemical equation:
MnO2 + HCI → MnCI2 + CI2 + H2O
What is meant by chemical reaction? Explain with the help of an example.
State one characteristic of the chemical reaction which takes place when quicklime is treated with water
What do you understand by exothermic reactions?
Write word equation for the following skeletal equation:
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Write word equation for the following skeletal equation:
\[\ce{KNO3 -> KNO2 + O2}\]
Balance the following chemical equation :
FeS + HCl → FeCl2 + H2S
Balance the following chemical equation :
H2 + O2 → H2O
Balance the following equation .
N2 + O2 → NO
What is a chemical equation? Why it is necessary to balance it?
Balance the following equation:
C + H2SO4 → CO2 + H2O + SO2
Sodium chloride reacts with silver nitrate to produce silver chloride and sodium nitrate
Write the equation.
Check whether it is balanced, if not balance it.
Find the weights of reactants and products.
State the law which this equation satisfies.
Write the balanced chemical equation of the following reaction.
copper + nitric acid → copper nitrate + nitric oxide + water
Write the balanced chemical equation of the following reaction.
ammonia + oxygen → nitric oxide + water
Write the balanced chemical equation of the following reaction.
aluminium carbide + water → aluminium hydroxide + methane
Write the balanced chemical equation of the following reaction.
potassium dichromate + sulphuric acid → potassium sulphate + chromium sulphate + water + oxygen.
(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 student mixes sodium sulphate powder in barium chloride powder. What change would the student observe on mixing the two powders? Justify your answer and explain how he can obtain the desired change.
In certain reaction a change of state is observed i.e. solid to liquid, liquid to gas etc. – State the change of state of the products – to give the respective reactant.
\[\ce{C +2S -> CS2}\]
In certain reaction a change of state is observed i.e. solid to liquid, liquid to gas etc. – State the change of state of the products – to give the respective reactant.
2H2 + O2 → 2H2O
In certain reaction an insoluble solid called precipitate is formed. State the colour and name of the precipitate formed in the following reaction involving addition of:
Iron [III] chloride to ammonium hydroxide.
Representation of the results of a chemical change – is a chemical equation.
For the equation: FeCl3 + 3NH4OH 3NH4Cl + Fe(OH)3 ↓
Answer the following:
Is the equation given above a balanced equation. Give reasons.
Give word equation for the following chemical reaction and give the names of the product formed.
Zn + 2HC1→ ZnCl2 + H2
Give word equation for the following chemical reaction and give the names of the product formed.
NH3 + HCl→ NH4Cl
Name the following:
The silvery residue obtained on heating mercury [II] oxide.
Balance the following simple equation:
C + O2 → CO
Balance the following simple equation:
N2 + O2 ⇌ NO
Balance the following simple equation:
H2 + O2 → H2O
Write a balanced equation for the following word equation:
Lead dioxide [lead (IV) oxide] → Lead monoxide + Oxygen
Write scientific reason.
Adding zinc particles to a solution of copper sulphate makes the blue solution colorless.
Balance the given chemical reaction as per the instructions below.
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Write names of reactants and products of chemical reaction.
What is called thermolysis reactions?
What is a product in a chemical equation?
