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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 following chemical equation.
\[\ce{NaCl + AgNO3 -> AgCl + NaNO3}\]
What does the symbol (aq) represent in a chemical equation?
How will you indicate Endothermic reaction in a chemical equation?
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.
Balance the given equation:
Mg(OH)2 + HCI MgCI + H2O
Fill in the following blank with suitable word:
A solution made in water is known as an ........... solution and indicated by the symbol ...........
What are the various ways in which a chemical equation can be made more informative? Give examples to illustrate your answer.
The removal of oxygen from a substance is called:
(a) oxidation
(b) corrosion
(c) reduction
(d) rancidity
Name the type of chemical reaction shown by the following equation:
2Mg+ O2 → 2MgO
Balance the following equation .
N2 + O2 → NO
Balance the following equation. Also name the product formed.
`"NaNO"_3 → "NaNO"_2 + "O"_2` Name of product (s)
Balance the equation stepwise.
Ag(s) + HCl(aq) → AgCl ↓+ H2 ↑
Show the formation of Na2O by the transfer of electrons.
State the information conveyed by the following equation:
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2 ↑
Write the chemical equation for the following word equation and balance them.
Magnesium + Sulphuric acid → Magnesium sulphate + Hydrogen
Balance the following equation:
Pb3O4 → PbO + O2
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.
\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
0.02 moles of pure MnO2 is heated strongly with conc. HCl. Calculate moles of acid required.
Write word equation for the following molecular equation:
CaO + H20 → Ca (OH)2 + Δ
Word equation:
State why [+ Δ ] is not written in the reaction, if ZnO reacts with H2O.
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 – lead [IV] oxide.
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 [II] sulphate to sodium hydroxide.
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:
Copper [II] sulphate to sodium hydroxide.
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:
Lead nitrate to ammonium hydroxide.?
Give one example in the case where supplying energy [given below] is necessary for a chemical reaction.
Electrical energy
Give word equation for the following chemical reaction and give the names of the product formed.
ZnCO3 → ZnO + CO2
Name the following:
The silvery residue obtained on heating mercury [II] oxide.
Name the following:
A catalyst which increases the rate of a chemical reaction.
Give an example of a chemical equation in which two reactants form:
three product
Balance the following simple equation:
H2S + Cl2 → S + HCl
Balance the following simple equation:
K + H2O → KOH + H2
Write a balanced equation for the following word equation:
Potassium nitrate → Potassium nitrite + Oxygen
Write a balanced equation for the following word equation:
Lead dioxide [lead (IV) oxide] → Lead monoxide + Oxygen
Write a balanced equation for the following word equation:
Potassium bicarbonate → Potassium carbonate + Water + Carbon dioxide
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
3CuO + NH3 → 3Cu + 3H2O + N2
Write an Explanation.
Balanced equations
Balance the given chemical reaction as per the instructions below.
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Make a list of the elements in the chemical equation.
Balance the following chemical equation.
- Na + O2 → Na2O3
- Ca + N2 → Ca3N2
- N2 + H2 →NH3
- CaCO3 +HCl → CaCl2 + CO2 +H2O
- Pb(NO3)2 → PbO + NO2 + O2
A student took a small amount of copper oxide in a conical flask and added dilute hydrochloric acid to it with constant stirring. He observed a change in colour of the solution.
- Write the name of the compound formed and its colour.
- Write a balanced chemical equation for the reaction involved.
Dil. HCl is added to Zn granules. How will you prove that chemical change has taken place here? Support your response with two arguments.
