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प्रश्न
Give reason for the following:
Though hydrogen is lighter than air it cannot be collected by downward displacement of air.
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उत्तर
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.
संबंधित प्रश्न
Fill in the blank
Hydrogen is ...................soluble in water.
Which metal is preferred for the preparation of hydrogen?
from acid?
What is noticed if the products are not allowed to escape?
Why hot concentrated sulphuric acid is not used in the preparation of hydrogen?
Give reason for the following:
Purified and dried hydrogen is collected over mercury.
Give reason for the following:
Dilute sulphuric acid cannot be replaced by concentrated acid in the preparation of hydrogen.
Hydrogen can be prepared with the help of cold water. Give a reaction of hydrogen with:
A monovalent metal
Hydrogen can be prepared with the help of cold water. Give a reaction of hydrogen with:
A divalent metal
Complete and balance the following reaction.
Na + H2O →_____________ +___________
Complete and balance the following reaction.
Zn + HCl →_____________ +___________
Complete and balance the following reaction.
Al + H2SO4 →_____________ +___________
Complete and balance the following reaction.
Al + KOH + H2O→_____________ +___________
Starting from hydrogen gas how would you obtain a basic gas.
Complete and balance the equation:
[General method]
Reactions of metals with dilute acids
Magnesium - Mg + 2HCl → ______+ _______ [g]
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.
Account for the following fact:
Potassium and sodium are not used to react with dilute ‘hydrochloric acid or dilute sulphuric acid in the laboratory preparation of hydrogen.
How did the name ‘hydrogen’ originate? How does hydrogen occur in the combined state?
Give a balanced equation for the following conversion.
\[\ce{KAlO2<-KOH->K2ZnO2}\]
Give a balanced equation for the following conversion.
\[\ce{ZnO<-H2O->Fe3O4}\]
