Dalal New Simplified Hydrogen First Element Class-9 ICSE Chemistry
Study of The First Element Hydrogen by Dr Viraf J Dalal Middle School Chemistry Allied Publishers
Dalal New Simplified Hydrogen-The Study of First Element, Class-9 ICSE Chemistry Solutions Chapter-6. We Provide Step by Step Solutions of Exercise/Lesson -6 The Study of First Element- Hydrogen with Additional Questions , Previous Year Questions and Unit Test-6 of Dr Viraf J Dalal Middle School Chemistry Allied Publishers New Simplified Chemistry . Visit official Website CISCE for detail information about ICSE Board Class-9.
Dalal New Simplified Hydrogen-The Study of First Element, Class-9 ICSE Chemistry Solutions Chapter-6
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Questions Previous Year Study of The First Element-Hydrogen Dalal New Simplified Chemistry
Name an element whsich reacts violently with water at room temperature.
Element reacts with water violently at room temperature is potassium.
What do the following symbols [or formula] denote : 2H ; H2 ; H+. [two atoms, molecule, ion] Answer:
2H donotes — 2 atoms of hydrogen
H2 — a molecule of hydrogen
H+ — an ion
Write correctly balanced equation for the following “word equation” :
calcium + water → calcium hydroxide + hydrogen
Ca + 2H2O → Ca[OH]2 + H2
When steam is passed over red-hot iron, magnetic oxide of iron and hydrogen are obtained. “The reaction between steam and red-hot iron is a Reversible Reaction.” What is meant by this statement.
Statement means magnetic oxide of iron and hydrogen recombine to form iron and steam.
How can you obtain hydrogen from sodium hydroxide [not by electrolysis].
When powdered zinc reacts with sodium hydroxide it produces hydrogen.
Write balanced equation for the following reaction : magnesium + dil. hydrochloric acid →
Mg + 2HCl (dil.) → MgCl2 + H2
Name a gas which burns in air or oxygen forming water.
The gas that burns in oxygen to form water is hydrogen.
Write correctly balanced equation for the following : When steam is passed over red hot iron.
Explain the following : Two jars of H2 are collected – “one burns quietly and the other does not”.
‘One bums quietly’ is pure hydrogen and ‘which does not bum quietly’ is mixed hydrogen with air it explodes on burning.
Write correctly the balanced equation for the following : ‘When zinc filings are added to a concentrated solution of sodium hydroxide’.
Describe one chemical test applied to the following gases, which would enable you to distinguish between them :‘carbon monoxide and hydrogen’.
Write down the “word equation” for the following reaction : sodium hydroxide solution + zinc →
Sodium hydroxide + zinc → Sodium zincate + hydrogen
Explain briefly how hydrogen is manufactured on a large scale, from steam.
Manufacture of H2 from steam :
From natural gas : Natural gas is obtained from petroleum wells and consists mainly CH4 (methane). It is mixed with steam at 30 atm. and passed over heated nickel 800°C, when water gas is formed.
State the products of the reaction “when steam is passed over red-hot iron”.
When steam is passed over red hot iron, teriferric tetroxide and hydrogen are the ; products formed.
How can you obtain hydrogen from a mixture of hydrogen and carbon monoxide.
See Q. 2. 1988. By dissolving the mixture in ammonical cuprous chloride. CO dissolves and H2 is left over.
What do you observe when a piece of sodium is dropped into cold water ?
When a piece of sodium metal dropped in cold water we observe : Sodium floats on water surface melts forming a silvery globule which darts about the surface of water catches fire and burns with golden yellow flame.
Bubbles of hydrogen evolve and solution is soapy, slightly warm (alkaline) hence turns red litmus blue.
Give reasons for the following : ‘Though hydrogen is lighter than air, it is not collected by the downward displacement of air’.
Though hydrogen is lighter than air it is not collected by displacement of air as it forms explosive mixture with air.
Complete the following word equations :
- Sodium hydroxide + zinc → hydrogen + ____
- Calcium + water → calcium hydroxide + ____
- Sodium hydroxide + zinc → hydrogen + sodium zincate
- Calcium + water → calcium hydroxide + hydrogen
How would you obtain ‘hydrogen from sodium hydroxide’ solution other than by electrolysis ?
By adding aluminium powder in cone, sodium hydroxide
Complete and balance the following equations :
Al + NaOH + ____ → ____ + ____
What do the following symbols represent : 2H and H2.
2H → represents → 2 atoms of hydrogen
H2 → represents → 1 molecule of hydrogen
Write balanced equation of the reaction in the preparation of : hydrogen from a solution of potassium hydroxide [other than by electrolysis].
Preparation of H2 from potassium hydroxide
Describe briefly, with equations, the Bosch Process for the large scale production of hydrogen.
Bosch process for large production of H2 :
Account for the following facts :
- Though lead is above hydrogen in the activity series, it does not react with dilute hydrochloric acid or dilute sulphuric acid.
- Potassium and sodium are not used to react with dilute ‘hydrochloric acid or dilute sulphuric acid in the laboratory preparation of hydrogen.
- Pb (lead) is above hydrogen in reactivity series. With dil. HCl, Pb forms PbCl2 and with dil. H2SO4, Pb forms PbSO4 both PbCl2 and PbSO4 are insoluble and forms respective coating to stop further reaction.
- Sodium and potassium with dil. HCl or dil. H2SO4 but reaction is highly explosive and practically not-feasible.
Place the metals calcium, iron, magnesium and sodium in order of their activity with water, placing the most active first. Write the equation for each of the above metals which react with Water.
Why is copper not used to prepare hydrogen by the action of dilute hydrochloric acid or dilute sulphuric acid on the metal, [copper [Cu] below hydrogen – no reaction] Answer:
Cu is below hydrogen in reactivity series and cannot displace H2 from acid and no-reaction takes place.
Additional Questions Study of The First Element-Hydrogen Dalal New Simplified Chemistry
State the electronic configuration of hydrogen [at. no. 1].e
Give a reason why hydrogen can be placed in group 1 [1A] and group 17 [VIIA] of the periodic table.
Electronic configuration of hydrogen is 1 i.e. it has le, IP in nucleus. Hydrogen can be placed in group 1[1A] as it forms a positive ion as in HC1 like alkali metals H