Worksheet solutions for chapter: Is Matter Around us Pure? for class 9 are provided below.
(1) What is concentration and give one formula to calculate it.
Ans- The amount of solute in per unit volume or per unit mass of the solution is called concentration of the solution.
Formula to calculate concentration of solution –
Mass by mass percentage of a solution = (Mass of the solute/Mass of the solution) 100
(2) Write differences between mixture and compound.
Ans- Differences between mixture and compound are tabulated below –
|a.||No new compound is formed by elements and compounds.||Elements react to form new compound.|
|b.||Has a variable composition.||Composition of each new substance is always fixed.|
|c.||Shows the properties of the constituent substances.||The new substance has totally different properties|
|d.||The constituents can be separated fairly easily by physical methods.||The constituents can be separated only by chemical or electrochemical reactions.|
|e.||Eg:- Air, milk etc.||Eg:- Methane, salt etc|
(3) Identify the phenomenon–
(i) Using sieve to separate tea and residue.
(ii) Getting colours from ink soluble in water.
(iii) Burning of camphor.
(i) Using sieve to separate tea and residue – Filtration
(ii) Getting colours from ink soluble in water – Chromatography
(iii) Burning of camphor – Sublimation
(4) Identify pure substances and mixture
(v) Jewelry of gold
|(v)||Jewelry of gold|
(5) What is solution and its parts.
Ans- Solution is a homogeneous mixture of two or more substances.
Eg:- Lemonade tastes same in every sip.
Components of the solution-
(a) The substance which dissolves the other substances is called solvent.
Eg: – In lemonade, water is solvent which dissolves lemon juice.
(b) The substance which dissolved in solution is called solute.
Eg:- In lemonade, lemon juice is solute which dissolved in water(solvent).
(6) Rita put some water on kerosene tub. Can she separate kerosene oil and water?
Ans- Rita can separate kerosene oil from water by using stopcock funnel separation method. She will take a separating funnel and fill it with mixture (water and oil) of tub. Let it stand undisturbed. After some time she will open up the stop cock of funnel and take out water from the mixture of kerosene oil and water. Close the stop cock, kerosene oil is inside the separating funnel which can be collected in different jar.
(7) Name the elements which are found liquid at room temperature and which are found liquid at slightly above room temperature.
Ans- Mercury and bromine are found liquid at room temperature. Gallium and cesium become liquid at a temperature slightly above room temperature.
(8) Find out physical and chemical changes among the given activities.
(i) A page from note book.
(ii) Cooked vegetable
(iii) Ashes of wood
(iv) Piece of fruit
|SN||Activities||Physical Change||Chemical Change|
|(i)||A page from note book||Yes|
|(iii)||Ashes of wood||Yes|
|(iv)||Piece of fruit||Yes|
(9) Differentiate between element and compound.
Ans- Differences between elements and compounds are tabulated below-
|(i)||Elements are basic form of matter||Compounds are composed of two or more elements which are chemically combined|
|(ii)||Elements can not be broken into simpler substances by chemical reactions.||Compounds can be broken by chemical reactions.|
|(iii)||Eg:- Silver, Copper etc.||Eg:- Water, sugar etc.|
(10) A solution contains 60 g of common salt in 400 g of water. Calculate the concentration in terms of mass percentage of the solution.