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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.
\[\ce{NaCl + AgNO3 -> AgCl + NaNO3}\]
Translate the following statement into a chemical equation and then balance it.
Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
What is wrong with the following chemical equation?
\[\ce{Mg + O -> MgO}\]
Correct and balance it.
Translate the following statement into a chemical equation and then balance the equation:
Aluminium metal replaces iron from ferric oxide, Fe2O3, giving aluminium oxide and iron.
Translate the following statement into a 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:
Ca(OH)2 + .......... \[\ce{-> CaCO3 + H2O}\]
Giving examples, state the difference between balanced and unbalanced chemical equations.
Give one example of a chemical reaction characterised by the formation of a precipitate.
State one characteristic of the chemical reaction which takes place when dilute sulphuric acid is added to barium chloride solution.
One of the following is an exothermic reaction. This is:
Balance the following chemical equation:
\[\ce{Pb(NO3)2_{(s)} ->[Heat] PbO_{(s)} + NO2_{(g)} + O2_{(g)}}\]
Write a balanced chemical equation with state symbols for the following reaction:
Barium chloride solution reacts with sodium sulphate solution to give insoluble barium sulphate and a solution of sodium chloride.
What happens when silver nitrate solution is added to sodium chloride solution?
- Write the equation for the reaction which takes place.
- Name the type of reaction involved.
Why do we need to balance chemical equations?
Balance the following equation. Also name the product formed.
`"NaNO"_3 → "NaNO"_2 + "O"_2` Name of product (s)
Balance the following equation. Also name the product formed.
`"H"_2 +"CI"_2 → "HCI"`
Write your observation and name the product when An aqueous solution of barium chloride is added to dilute sulphuric acid.
Complete the following equation:
CH4 + O2 —>
Complete the following equation:
CH3COOH + NaOH →
A student weighed some raisins and recorded the weight as ‘x’. She then soaked the raisins in distilled water. After about 2 hours she removed the raisins, wiped them dry and weighed them again, and recorded that as ‘y’. The percentage of water absorbed by raisins may be determined using the relationship.
Show the formation of Na2O by the transfer of electrons.
Balance the following equation:
HNO3 + H2S → NO2 + H2O + S
What information does the following chemical equation convey?
Zn + H2SO4 → ZnSO4+ H2
What is the valency of :
carbon in CH4
Write the balanced chemical equation of the following reaction.
zinc sulphide + oxygen → zinc oxide + sulphur dioxide
Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Zinc reacts with silver nitrate to produce zinc nitrate and silver.
1 g of copper powder was taken in a China dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equations of reactions, the name and the color of the products formed in each case.
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.
Write word equation for the following molecular equation:
\[\ce{NH3 [g] + HCl [g] ⇌ NH4Cl [s]}\]
Word equation:
State which characteristic is observed in the above reaction.
Give an-example of a similar above characteristic, seen between two other gaseous reactants.
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 – mercury [II] oxide.
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.
\[\ce{2H2O ->[electric][current] 2H2 + O2}\]
Representation of the results of a chemical change – is a chemical equation.
For the equation: FeCl3 + 3NH4OH 3NH4Cl + Fe(OH)3 ↓
Answer the following:
Write the word equation for the above molecular equation.
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.
NH3 + HCl→ NH4Cl
Name the following:
Two non-metal which react explosively when brought in close contact.
\[\ce{2KClO3->[MnO2] 2KCl + 3O2[g] - is a balanced equation.}\]
State what is a ‘balanced equation’.
Balance the following simple equation:
\[\ce{Ca(OH)2 + HNO3 -> Ca(NO3)2 + H2O}\]
Writing a chemical reaction in brief by using chemical formulae is called as _______.
