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Question
Give reason for the following:
Though hydrogen is lighter than air it cannot be collected by downward displacement of air.
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Solution
Since hydrogen is lighter than air. it is possible to collect the gas by downward displacement of air. But it is not safe to do so since a mixture of hydrogen and air can lead to an explosion.
RELATED QUESTIONS
Name the following:
Two metals which give hydrogen with cold water.
Match the statements in Column A with those in Column B.
| Column A | Column B |
|
1. A metal which reacts with cold water to from hydrogen. |
1. Reduction |
| 2. A gas which is inflammable and non-supporter of combustion | 2. Hydrogenation |
|
3. A process in which vanspati ghee is prepared from vegitable oils |
3. oxidation |
|
4. The removal ofhydrogen or addition of oxygen |
4. sodium |
| 5. The addition of hydrogen or removal of oxygen | 5. Hydrogen |
TRUE \ FALSE
Hydrogen does not combine with nitrogen under ordinary conditions.
How do different metals displace hydrogen from water? Explain with the help of equations.
Why nitric acid is not used in the preparation of hydrogen?
Where does hydrogen occur in a free state?
Why are the following metals not used in the lab. preparation of hydrogen?
aluminium
Why are the following metals not used in the lab. preparation of hydrogen?
sodium
Complete and balance the following reaction.
Al + KOH + H2O→_____________ +___________
Give reason:
A candle brought near the mouth of a jar containing hydrogen gas starts burning but is extinguished when pushed inside the jar.
Select the correct options for the following statement:
The metal used as a catalyst in hydrogenation of oils.
Select the correct options for the following statement:
The product formed on combustion of hydrogen in air is ___.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
An efflorescent substance which leaves a residue having the same colour as the substance and evolves a gas which changes the colour of cobalt chloride paper.
Complete and balance the equation:
[General method]
Reactions of metals with steam
Iron - 3Fe + 4H2O ⇌ ______+ _______ [g]
Complete and balance the equation:
[General method]
Reactions of metals - alkali [conc. soln.]
Lead - Pb + 2NaOH → ______ + _______ [g]
Complete and balance the equation:
[Industrial Method - Bosch process]
- Step I - Production of water gas -
\[\ce{C + H2O->[1000°C]}\] [____ + ____] - Δ - Step II - Reduction of steam to hydrogen by carbon monoxide
\[\ce{CO + H2 + H2O->[450°C][Fe2O3]}\] _____ + ____ [g] - Step III - Removal of unreacted carbon dioxide and carbon monoxidefrom the above mixture
KOH + CO2 → _________ + ______
CuCl + CO + 2H2O → _______
Account for the following fact:
Though lead is above hydrogen in the activity series, it does not react with dilute hydrochloric acid or dilutes sulphuric acid.
Select the correct answer to the reactant added, to give the product in the preparation of hydrogen gas.
\[\ce{NaAlO2 + H2}\]
Give a balanced equation for the following conversion.
\[\ce{MgCl2<-HCl->FeCl2}\]
