Advertisements
Advertisements
Question
Grills of doors and windows are always painted before they are used.
Advertisements
Solution
- 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.
APPEARS IN
RELATED QUESTIONS
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.
Correct and balance the following equations:
\[\ce{N + H -> NH3}\]
Balance the following equation:
\[\ce{BaCl2 + H2SO4 -> BaSO4 + H2O}\]
Chemical equations are balanced to satisfy the law of ______.
Aluminium burns in chlorine to form aluminium chloride (AlCl3). Write a balanced chemical equation for this reaction.
Explain, with an example, how the physical states of the reactants and products can be shown in a chemical equation.
Write a balanced chemical equation for the process of photosynthesis giving the physical states of all the substances involved and the conditions of the reaction.
When potassium nitrate is heated, it decomposes into potassium nitrite and oxygen. Write a balanced equation for this reaction and add the state symbols of the reactants and products.
What is meant by a chemical reaction? Explain with the help of an example.
The chemical reaction between two substances is characterised by a change in colour from orange to green. These two substances are most likely to be ______.
When a mixture of gases X and Y is compressed to 300 atm pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300°C), then an organic compound Z having the molecular formula CH4O is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.
- What are X, Y and Z?
- Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.
Express the following facts in the form of a balanced chemical equation:
“When a strip of copper metal is placed in a solution of silver nitrate, metallic silver is precipitated and a solution containing copper nitrate is formed”.
What is a chemical equation?
Balance the following chemical equation :
Na20 + H20 → NaOH
Balance the following equation .
N2 + O2 → NO
Balance the following equation. Also name the product formed.
`"KCIO"_3 → "KCI" +"O"_2`
Balance the following equation. Also name the product formed.
`"CO" + "O"_2 → " CO"_2`
Balance the following equation. Also name the product formed.
FeCI2 + CI2 → FeCI3
While performing the experiment with raisins to determine the percentage of water absorbed by them, a student made following measurements:
Mass of water in the beaker = 40 g
Mass of raisins before soaking = 5 g
Mass of raisins after soaking for 2 hours = 8 g
Mass of water left in the beaker after the experiment = 35 g
The percentage of water absorbed by raisins is:
Show the formation of Na2O by the transfer of electrons.
What do the following symbol stand for?
2H2
Balance the following equation:
PbS + O2 → PbO + SO2
Write the balanced chemical equation of the following reaction.
iron pyrites(FeS2) + oxygen → ferric oxide + sulphur dioxide
Write the balanced chemical equation of the following reaction.
potassium dichromate + hydrochloric acid → Potassium chloride + chromium chloride + water + chlorine
Write the balanced chemical equation of the following reaction.
sodium chloride + manganese dioxide + sulphuric acid → sodium hydrogen sulphate + manganese sulphate + water + chlorine.
\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]
0.02 moles of pure MnO2 is heated strongly with conc. HCl. Calculate moles of acid required.
How is a flame test performed?
Choose the correct alternative and rewrite the following sentence.
Which of the following is not required to find the pH of a given solution?
Answer the following question:
How do acids and bases react with each other? What is the name of the process? What product is obtained from these reactions?
What is thermit process?
Write word equation for the following molecular equation:
AgN03 + HCI → HNO3 + AgCl ↓
Word equation:
State whether AgCl is soluble or insoluble in HN03.
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.
NH3 + HCl ⇌ NH4Cl
Representation of the results of a chemical change – is a chemical equation.
For the equation: FeCl3 + 3NH4OH 3NH4Cl + Fe(OH)3 ↓
Answer the following:
What is the indications of the arrow between the reactants and the products and of the arrow pointing downwards at the end.
Give reason for the following:
Silver salts are kept in dark coloured bottles.
Balance the following simple equation:
\[\ce{N2 + H2 <=> NH3}\]
Give a balanced equation by the partial equation method, [steps are given below].
Oxidation of Lead [II] Sulphide by Ozone
- Ozone first decomposes to give molecular oxygen & nascent oxygen.
- Nascent oxygen then oxidises lead [II] sulphide to lead [II] sulphate.
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
CaC2 + N2 → 2CaCN2 + C
When aqueous solutions of potassium iodide and lead nitrate are mixed an insoluble substance separates out. The chemical equation for the reaction involved is:
