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प्रश्न
Give a reason for the following.
Hydrogen is collected by the downward displacement of water and not of air, even though it is lighter than air.
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उत्तर
Hydrogen is collected by the downward displacement of air because of
- It is insoluble in water.
- It forms an explosive mixture with air.
संबंधित प्रश्न
Complete the following word equation:
Calcium + water → calcium hydroxide + _________
Give reason for the following:
Potassium and sodium are not used for reaction with dilute hydrochloric acid or dilute sulphuric acid in the laboratory preparation of hydrogen.
Name two alkalies that can displace hydrogen. Give balanced equations for the same. Why are the metals you have used considered to have a unique nature?
Write a balanced equation for the reaction named metal with (i) boiling water (ii) steam.
When hydrogen is passed over a black solid compound A, the products are a 'colorless liquid' and a 'reddish-brown metal B'.
Substance B is divided into two parts each placed in separate test tubes.
Dilute HCl is added to one part of substance B and dilute HNO3 to the other.
- Name the substances A and B.
- Give two tests for the colourless liquid formed in the experiment.
- What happens to substance A when it reacts with hydrogen? Give reasons for your answer.
- Write an equation for the reaction between hydrogen and substance A.
- Is there any reaction between substance B and dilute hydrochloric acid? Give reasons for your answer.
Select the odd one out and justify your answer.
Zn, Fe, Mg, and Na
Which of the following metals does not give hydrogen with acids?
Choose terms from the options given in brackets to complete this sentence.
Sodium ………………. reacts smoothly with cold water.
(metal, amalgam, in the molten state)
Correct the following statement:
Very dilute nitric acid reacts with iron to produce hydrogen.
State why hydrogen is not prepared in the laboratory by the action of calcium with dilute sulphuric acid.
