Question:
What are the constituents of brass?
Answer:
Brass is an alloy and is a mixture of Zinc(30%) and Copper (70%).
Is Matter Around Us Pure?
Q 1.
What is the general name of the process by which tea-leaves are separated from prepared tea ?
Q 2.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 3.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 4.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 5.
Name one pair of liquids which can be separated by using a separating funnel.
Q 6.
Define Brownian movement in colloids.
Q 7.
What is saturated solution? Explain with an example.
Q 8.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293K. Find its concentration at this temperature.
Q 9.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 10.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 11.
What is an unsaturated solution?
Q 12.
Name the elements are in liquid state at room temperature.
Q 13.
Who used the term 'element' first time?
Q 14.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 15.
What is meant by saying that metals are malleable and ductile ?
Q 16.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 17.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 18.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 19.
What is an emulsion? Give examples
Q 20.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
Q 21.
Name a non-metal which is a good conductor of electricity.
Q 22.
Give two reasons for supposing that water is a compound and not a mixture.
Q 23.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 24.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 25.
What are non-aqueous solutions?
Q 26.
Explain with an example what is a colloid?
Q 27.
How are sol, solution and suspension different from each other?
Q 28.
What are the differences and similarities between concentration and solubility?
Q 29.
Name a metal which is soft and a non-metal which is hard.
Q 30.
Name a metal :
(a) which can be easily cut with a knife
(b) which forms amalgams
©which has not fixed shape
(d) which has a low melting point
(e) which is yellow in colour
Q 31.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 32.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 33.
What are different categories of pure substance?
Q 35.
State the differences between compounds and mixtures.
Q 36.
Based on the type of solvent, how solutions are classified?
Q 37.
How crystallization is better than evaporation?
Q 38.
State whether the following statement is true or false : Milk is a pure substance.
Q 39.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 40.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 41.
Which of the two will scatter light: soap solution or sugar solution ? Why ?
Q 42.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 43.
A 5 per cent sugar solution means that:
(a)5 g of sugar is dissolved in 95 g of water.
(b)5 g of sugar is dissolved in 100 g of water.
Choose the correct answer.
Q 44.
(a) What is a physical change ? Give two examples of physical changes.
(b) What is a chemical change ? Give two examples of chemical changes.
Q 45.
How will you separate a mixture of chalk powder and water ?
Q 46.
Name the process which is used in milk dairies to separate cream from milk.
Q 47.
(a) Name the process by which all the dye can be recovered from black ink.
(b) Name the process by which the various dyes' (coloured materials) present in black ink can be separated.
Q 48.
How will you separate iron pins from sand ?
Q 49.
Name two properties of a substance to check its purity?
Q 50.
What are the kinds of mixture?
