Viraf J. Dalal solutions for New Simplified Middle School Chemistry [English] Class 8 chapter 3 - Elements, Compounds & Mixtures [Latest edition]

Represent with the help of a simple chart how matter is classified into pure or impure substances & further into elements, compounds & mixtures, with elements further segmented.

Define the terms elements, compounds & mixtures with a view to show their basic difference.

‘An atom is the basic unit of an element’. Draw a diagram of an atom – divisible as seen today.

‘The modern periodic table consists of elements arranged according to their increasing atomic numbers’. With reference to elements with atomic numbers 1 to 20 only in the periodic table – differentiate them into – metallic elements, metalloids, non-metals & noble gases.

Elements are broadly classified into metals and non-metals. State six general differences in the physical properties of metals and non-metals. State two metals and two non-metals which contradict with the general physical properties – giving reasons. State one difference in property between metalloids and noble gases.

With reference to elements – define the term ‘molecule’. Give two examples each of a monoatomic, diatomic & polyatomic molecule.

Define the term ‘compound’. In the compound carbon dioxide – the elements carbon & oxygen are combined in a fixed ratio. Explain.

State five different characteristics of compounds.

Give three differences between elements & compounds with relevant examples.

Explain the term ‘mixture’.

Differentiate between homogenous & heterogeneous mixtures.

State why brass is considered as a homogenous mixture while a mixture of iron & sulphur – heterogenous.

Give an example of two liquids that form heterogeneous – mixtures.

Give an example of two liquids which form homogenous.

Compare the properties of iron [II] sulphide with the iron-sulphur mixture, considering iron [II] sulphide as a compound & particles of iron & sulphur mixed together as an example of a mixture.

State any one method – to separate the following mixtures – Two solid mixtures one of which – directly changes into vapour on heating.

State any one method – to separate the following mixtures – Two solid mixtures one of which – dissolves in a – particular solvent and other does not

State any one method – to separate the following mixtures – A solid-liquid mixture containing an insoluble solid in the liquid component

State any one method – to separate the following mixtures – A solid-liquid mixture containing – a soluble solids in the liquid component

State any one method – to separate the following mixtures – A liquid-liquid mixture containing – two immiscible'' liquids having different densities

State any one method – to separate the following mixtures – A liquid-liquid mixture containing – two miscible liquids having different boiling points.

State any one method – to separate the following mixtures – A liquid-gas mixture containing – a gas dissolved in a liquid component.

State any one method – to separate the following mixtures – A gas-gas mixture containing – two gases with different densities.

State any one method – to separate the following mixtures – A mixture of different solid constituents – in a liquid constituent.

Explain with diagram the process used to – separate the following substance from the given mixtures - Ammonium chloride from a mixture of – ammonium chloride & potassium chloride.

Explain with diagram the process used to – separate the following substance from the given mixtures - Iron from a mixture of – iron & copper

Explain with diagram the process used to – separate the following substance from the given mixtures - Sulphur from a mixture of – sulphur & copper.

Explain with a diagram the process used to – separate the following substance from the given mixture.

Potassium nitrate from a mixture of – potassium nitrate & potassium chlorate.

Explain with a diagram the process used to – separate the following substance from the given mixture.

Lead carbonate [insoluble] from a mixture of – lead carbonate & water.

Explain with diagram the process used to – separate the following substance from the given mixtures - Lead nitrate [soluble] from a mixture of – lead nitrate & water Le. lead nitrate solution.

Explain with diagram the process used to – separate the following substance from the given mixtures - Carbon tetrachloride from a mixture of – carbon tetrachloride [heavier component] & water.

Explain with diagram the process used to – separate the following substance from the given mixtures - Benzene from a mixture of – benezene [b.p. 80°C] & toluene [b.p. 110°C].

Explain with diagram the process used to – separate the following substance from the given mixtures - Different dyes – in their liquid constituent ink.

Select the correct answer from A, B, C, D & E for the statement given below :

A diatomic molecule.

Select the correct answer from A, B, C, D & E for the statement given below :

A metalloid.

Select the correct answer from A, B, C, D & E for the statement given below :

A non-metal that is lustrous.

Select the correct answer from A, B, C, D & E for the statement given below :

A mixture consisting of elements & a compound.

Select the correct answer from A, B, C, D & E for the statement given below :

A noble gas.

Match the separation of components in List I with the most appropriate process in List II.

The diagram represents fractional distillation for the separation of mixtures. Answer the following :

1. Can two immiscible liquids be separated by this process?
2. Separation of liquids by this process is based on which physical property?
3. If methyl alcohol & water are to be separated, which liquid would remain in flask ‘X’ after condensation.
4. Give a reason for the above answer.
5. State the purpose of the fractionating column in the apparatus.

Select the correct answer from the choice given below to complete the sentence :

Dust in air is an example of _________ mixture.

Select the correct answer from the choice given below to complete the sentence :

A soluble solid is separated from an insoluble solid by ____________.

Select the correct answer from the choice given below to complete the sentence :

The reactive element from the two monoatomic elements is _____________.

Select the correct answer from the choice given below to complete the sentence :

Compounds are ____________ in nature.

Select the correct answer from the choice given below to complete the sentence :

An example of a monoatomic molecule is ___________.

Give a reason for the following statement :

Components in a mixture can be separated by physical methods only.

Give a reason for the following statement :

Centrifugation can be used for separating an insoluble heavier solid, present in an – insoluble solid-liquid mixture.

Give a reason for the following statement :

The filter paper made into a cone & placed in a funnel for filtering out the solid particles in a solid-liquid mixture should be moistened before placing it.

Give a reason for the following statement :

Brass & bronze are examples of mixtures, while copper sulphate & lead nitrate are examples of compounds.

Give a reason for the following statement :

Zinc is considered an element, while zinc sulphide is considered a compound.