Viraf J. Dalal solutions for New Simplified Middle School Chemistry [English] Class 8 chapter 7 - Hydrogen [Latest edition]

State how hydrogen occurs in the free state. Name three compounds containing hydrogen in the combined state.

Starting from zinc how would you obtain hydrogen using Steam.
[Give balanced equation & name the product formed in the case other than hydrogen].
Name a metal which will not react with the reactants above to give hydrogen.

Starting from zinc how would you obtain hydrogen using a dilute acid. 
[Give balanced equation & name the product formed in the case other than hydrogen].
Name a metal which will not react with the reactants above to give hydrogen.

Starting from zinc how would you obtain hydrogen using an alkali. 
[Give balanced equation & name the product formed in the case other than hydrogen].
Name a metal which will not react with the reactants above to give hydrogen.

‘Hydrogen is obtained by electrolysis of acidified water’.
Answer the following pertaining to the preparation of hydrogen by electrolysis,
The meaning of the term ‘electrolysis’ and ‘electrolyte’.

‘Hydrogen is obtained by electrolysis of acidified water’.
Answer the following pertaining to the preparation of hydrogen by electrolysis,

Name the electrode –

1. through which the current enters the electrolyte.
2. at which hydrogen is liberated.

In the laboratory preparation of hydrogen from zinc & dilute hydrocholoric acid – state a reason for the addition of traces of copper [II] sulphate to the reaction medium.

In the laboratory preparation of hydrogen from zinc & dilute hydrocholoric acid – state a reason for the collecting the hydrogen by downward displacement of water and not air & collecting it after all the air in the apparatus is allowed to escape.

In the laboratory preparation of hydrogen from zinc and dil. acid. Give a reason for the following:

The lower end of the thistle funnel should dip below the level of the acid in the flask.

In the industrial method of preparation of hydrogen by the Bosch process give the balanced equations for the first two main steps in the production of hydrogen.

In the industrial method of preparation of hydrogen by the Bosch process give the reason for use of addition of a promoter to the catalyst in the final step.

In the industrial method of preparation of hydrogen by the Bosch process give the name of the solution which absorbs the unreacted carbon monoxide.

State the following pertaining to the physical properties of hydrogen: Colour & odour

State the following pertaining to the physical properties of hydrogen: Solubility in water

State the following pertaining to the physical properties of hydrogen: Effect on moist blue litmus paper.

Draw neat labelled diagrams for two different experiments to prove that – hydrogen is lighter than air.

Starting from hydrogen gas how would you obtain a neutral liquid.

Starting from hydrogen gas how would you obtain a basic gas.

Starting from hydrogen gas how would you obtain a metal by reduction of its heated oxide.

Using a burning candle and a jar of hydrogen – how would you prove experimentally that Hydrogen is a combustible gas.

Using a burning candle and a jar of hydrogen – how would you prove experimentally that Hydrogen does not support combustion.

State a reason why, when hydrogen is passed over heated copper oxide, the resultant product formed, differs in colour from the original reactant.

With reference to the uses of hydrogen, give reason for the following:

Hydrogen is not used in air balloons

With reference to the uses of hydrogen, give reason for the following:

A mixture of hydrogen & oxygen on burning, find application in welding & cutting metals.

With reference to the uses of hydrogen, give reason for the following:

Reaction of hydrogen with nitrogen under specific conditions finds industrial utility.

Give a test to differentiate between two gas jars – one containing pure hydrogen and the other hydrogen-air mixture.

With reference to oxidation & reduction reaction – complete the statement given by filling in the blanks with only the words (a) Addition (b) Removal.

‘Oxidation is a chemical reaction involving ____ of oxygen to a substance or ____ of hydrogen from a substance. Reduction on the otherhand involves ____ of hydrogen to a substance or ____ of oxygen from a substance.

With reference to the equation : Cl₂ + H₂S → 2HCl + S pertaining to a redox reaction – select the correct answer.

Chlorine is ______ to HCl.

With reference to the equation : Cl₂ + H₂S → 2HCl + S pertaining to a redox reaction – select the correct answer.

Hydrogen sulphide is ______ to sulphur since the reaction involves ______ of hydrogen.

With reference to the equation : Cl₂ + H₂S → 2HCl + S pertaining to a redox reaction – select the correct answer.

Chlorine acts as an ______ agent.

Give balanced equation for the following conversion:

Zinc to sodium zincate – using an alkali.

Give balanced equation for the following conversion:

Acidified water to hydrogen – by electrolysis.

Give balanced equation for the following conversion:

Water gas to hydrogen – industrially.

Give balanced equation for the following conversion:

Iron [III] oxide to iron – using hydrogen.

Give balanced equation for the following conversion:

Nitrogen to a basic gas – using hydrogen.

Give reason for the following:

Copper does not displace hydrogen from dilute hydrochloric acid, but zinc does.

Give reason for the following:

In the preparation of hydrogen by electrolysis of water – the distilled water used is acidified.

Give reason for the following:

In the laboratory preparation of hydrogen from zinc and dilute hydrochloric acid – the zinc used granulated zinc.

Give reason for the following:

In Bosch process – the final gaseous products are passed through caustic potash [KOH] soln.

Give reason for the following:

The reaction of chlorine with hydrogen sulphide is deemed a redox reaction.

Select the correct options for the following statement:

A metal which reacts with water to give a metallic hydroxide & liberate hydrogen.

Select the correct options for the following statement:

The metallic compound used as a catalyst in Bosch process.

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 metal which reacts with steam liberating hydrogen & the reaction is reversible.

Select the correct options for the following statement:

The metallic compound formed when a metal above aluminium in the activity series reacts with steam.

Select the correct options for the following statement:

The acid _____ is not Used in the laboratory preparation of hydrogen, using zinc and an acid.

Select the correct options for the following statement:

In Bosch process the catalytic reduction of steam to hydrogen is carried out by ___.

Select the correct options for the following statement:

A foul smelling gas formed when hydrogen reacts with a molten non-metal, is ___.

Select the correct options for the following statement:

The product formed on combustion of hydrogen in air is ___.

Select the correct options for the following statement:

The gas which has now replaced hydrogen in air balloons is ___.

Match the statements in List I with the appropriate answer in List II.