CBSE Class 6th Solutions
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Ncert – Class 7th – Chapter 6th – Solution- Physical And Chemical Changes

Ncert -Chapter 6th – Solution- Physical And Chemical Changes

In this post we will see  class 7th Science  – Physical And Chemical Changes based on NCERT. It can be used for all the students studying in CBSE boards or any board which are using the NCERT books for their syllabus. All the answers are prepared by Expert teachers and are very useful for all the board using NCERT like CBSE, State boards.

Also Class 7th Science All chapters solutions here –

EXERCISE -1 – Answer In Brief 

Question – 1st What is an element ?

Solution –   An element is a substance that can be spilt  into simpler by chemical method

Question – 2nd Define  an atom and a molecule ?

Solution – The smallest particle of an element that retains the property of the element called a atom  a molecule is the smallest part of an element or compound that can exit by itself

Question – 3rd What is the formula of nitric acid ?

Solution –  HNO3

Question – 4th  Compound A reacts with another compound B ?

Solution – A chemical change present when compound a reacts with another compound B to make compound C

Question – 5th What compound  of these formula represent H2O ,CO2 , Cuso4 . Nhco3 ?

Solution –  Water represent= H2O  carbon dioxide= CO2 Copper sulphate= Cuso4 Sodium bicorbanate = Nahco3

Question – 6th What is crystillation ?

Solution – Crystillation is the process of sepearting solid from its solution as crystillation

Question – 7th Write the chemical equation in words ?

Solution – Iron +Copper sulphate = copper +Iron sulphate Fe +Cuso4  =  cu +Feso4

Question – 8th How an browing of the cust surfaces of some fruit and vegetable ?

Solution – The browing of cut fruit can be prevented by rubbing lemon juice on the cust surface or by placing cut fruit under water to prevent contant with oxygen

Exercise – 2nd Answer in detail 

Question – 1st  Explain with the help of an example the difference between a atom and a molecule ?

Solution – Atom the smallest particle of an element each element is made of only one kind of  atom the atom of an one element are difference form of atom of any other element a molecule may contain one or more atoms a molecule of an atom contain similar atoms .

Question – 2nd List main three properties of all compound ?

Solution – Properties of compound ; –

A composition of a specfic is fixed irrespective of how and where it is made .

Sepretion – ;-

A compound cannot be broken down to its constitued element by physical method  of seperation .

Properties – Different from constitute element the properties of compound of there consituent element ?

Question  – 3rd Define a physical change and list its charactercises ?

Solution – Physical change ; –

Change that affect only the physical properties of a substance and where no new substance are formed are called physical change

[1] Melting of butter

[2] Tearing of paper

[3] Breaking of glass

[4] Dissolution of sugar in water

Question – 4th Define a chemical change  and list the character ?

Solution – Change that involve the formation of a new substance are called chemical change the burning of paper curding of milk .

Exercise – 3rd Multiple choice question 

[1] The smallest  particle of a compound that can exit in nature is called

[1] Atom             [2] Molecule            [3] Element         [4] Mixture

Answer – Atom 

[2] The chemical symbol of arsneic acid is _________

[1] A                        [2] Ar                             [3] As                   [4] An

Answer – AS 

[3] The valency of helium and calcium are ____________________ Respectively

[1] 0 and 1                 [2] 1 and 0                  [3] 1 and 2               [4] 0 and 2

Answer – 0 and 2

[4] Sulphate  is an /a __________

[1] Element                        [2]  molecule            [3]  Group of atoms       [4] compound

Answer – Group of atoms 

[5] Which of these is an chemical change ?

[1] The dissolution of sugar in water

[2] Water freezing to ice

[3] the melting of ice

[4] The burning of a candle

Answer – The burning of a candle 

[6] The burning of wax is an example of a /an ___________ change ?

[1] Irreversible and chemical                                          [2] Reversible and physical

Answer  – Irreversible and chemical

[7] Rusting is the change of __________

[1] Iron oxide to iron

[2] oxygen to carbon dioxide

[3] Iron to iron oxide

[4] carbon dioxide to oxygen

Answer – Iron to iron oxide 

[8] The browning of the cut surface of fruit is similar to ________________

[1] Evaporation                [2] Condenstion              [3] Rusting                              [4]  Crystillation

Answer – Rusting 

Exercise –  4th Fill In The Blanks 

[1] There are  ________elements known till now .    Answer     –   [ 118]

[2] Common salt is made of _____________ and ______________ .         Answer     –       [ Sodium and chlorine]

[3] The properties of compound are different from the properties of there constituent _____________ . Answer      –    [ Elements]

[4] Melting of wax is a / an  ____________ change .          Answer                 –      [ Physical]

[5] The process that takes place  when a supersaturated solution of urea is cooled to get the solute is called  __________ .             Answer                     –       [ crystallisation  ]

[6] Iron nails dipped in a solution of copper sulphate acquire a reddish – brown copper colour. this is an example

of a _____________ change  .               Answer                            –  [chemical ]

[7] The chemical formula of calcium carbonate is __________ .    Answer        –         [Caco3]

[8] Cuso4 is the chemical formula of ___________ . Answer                –      [Copper sulphate]

Exercise – 5th True or False 

[1] An element is made of only one kind of atom . Answer – [ True]

[2] Carbon dioxide is made of carbon and oxygen . Answer – [ True]

[3] A mixture is a substance that has two or more elements in a fixed ratio . Answer – [True]

[4] the compenet of a mixture retain their properties in a mixture . Answer – [True]

[5] A symbol can be used to represnt an element or an atom of an element .Answer – [True]

[6] The number of atoms in a molecule of an element is called its formula .Answer – [ false]

[7] Rusting is a physical change . Answer – [ True]

[8] A physical change can be reversible or irresvible. Answer –  [ False]

[9] Crystillation is an irresvible change . Answer – [True] 

 

you can check Previous Chapter Solutions here –

Also Class 7th Science All chapters solutions here –

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