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Which of the following statements is/are correct?
I. Larger solid particles can be separated from smaller ones by filtration.
II. Cream can be separated from milk by churning.
Ill. A mixture of mud and water can be separated by loading, sedimentation and decantation.
IV. Grains can be separated from stalks by threshing.
Larger solid particles are separated from smaller ones by sieving.
Which of the following does not represent a characteristic of pure substance?
A pure substance is made up of only one type of particles.
What are the characteristics of metals?
1.Metals are Malleable- This means that metal can be beaten into thin sheets with hammer(without breaking).Gold and siver are best malleable metals.Aluminium and copper are highly malleable metals. All the metals can be beaten with hammer to form thin sheets called foils.Ex-Silver is converted into thin sheets to form silver foils which is used to decorating sweets.
2.Metals are ductile- This means that metals can be drawn into thin wires.Gold and silver are best ductile metals.Ex-100 milligrams of silver can be drawn into thin wire about 200 m.Copper and aluminium are also very ductile.
3.Metals are good conductor of heat and electricity-Metals allow heat and electricity to pass through them very easily.Metals are good conductor of heat .They has the highly thermal conductivity.Copper and aluminium are best among them.that’s why cooking utensils are made up of copper and aluminium.
Metals are good conductor of electricity .Copper and aluminium are best among them .That’s why electric wire is made up of copper and aluminium.
4.Metals are lustrous-Gold,silver are shiny metals and they can be polished. The shiny appearance makes them useful in making jewellery
5.Metals are sonorous-This means that metals make a ringing sound when we strike them.Due to this property metals are used for making bells.
6.Metals are solid at room temperature-All the metals are solid at room temperature(except mercury).
Select an incorrect reason for separating components of a mixture.
Mixtures are usually separated to obtain a particular substance that we need or to get rid of one or more unwanted substances.
Match the column I with column II and select the correct option from the codes given below:
Take 10 mL of water in 6 test tubes each and add different samples of substances to each test tube as shown in the given figure. Shake the test tubes vigorously for a couple of seconds and leave them undisturbed. In which of these test tubes, sample substances will remain insoluble
Sand, chalk powder and sawdust are insoluble in water. They settle down in the test tubes. Sugar, salt and washing powder are soluble in water.
Three groups of materials are given below:
I Salt, sugar, flour
II Copper, gold, silver
III Petrol, kerosene, paper
Identify the property common to each group
Salt, sugar, flour - Edible Copper, gold, silver - Metallic Petrol, kerosene, paper - Inflammable.
Match the column I with column II and select the correct option from the codes given:
Chalk-water mixture -A heterogeneous solid-liquid mixture Glucose solution - A homogeneous solid- liquid mixture Fizzy drink - A gas-liquid mixture Smoke - A solid-gas mixture Air - A gaseous mixture
A few statements about centrifugation method are given:
I. The mixture containing very small suspended particles is rotated at a high speed in a centrifuge machine.
II. The denser particles stay at the top.
Ill. The method is used to separate water from wet clothes in a washing machine.
IV. The method can be used in laboratories for separating plasma and platelets.
The correct statements are
Denser particles stay at the bottom.
Shobha took two liquids (coconut oil and water) in a separating funnel as shown in the figure. What would she observe after some time?
Oil and water are immiscible liquids and form two distinct layers in which oil floats on the top of water.
Study the given table showing some daily D used items which can be made from more than one material.
Which of these are incorrect?
Both cooking pot and LPG cylinder cannot be made from wood, plastic and glass. Besides, tea cups are generally made of glass, ceramic and porcelain, etc.
A science teacher labelled three glass slides as P, 0 and R. She painted slide Q with light blue colour, slide R with black colour and slide P was left as such. Then she asked students to put the slide on a white paper having (X) mark on it. Students will be able to see the mark clearly (or partially)
Slide P is transparent, Q is translucent and R is opaque.
Depending upon the nature of the constituents present in a mixture, Suhana, a class 6 student suggested some methods of separation as shown in the table.
Which of these is/are incorrect method(s) of separation?
Soluble solid - liquid mixture cannot be separated by filtration and decantation. It can be separated by evaporation.
Study the given flowchart carefully.
P, Q and R could be respectively
In the mixture of sugar, water and sawdust, firstly sawdust (R) being insoluble in water, is removed by filtration and then sugar (P) is separated from water (Q) by evaporation.
Four rods of equal length and thickness but of different materials are coated with wax in the same manner. They are fixed to a trough containing hot water. The given diagram illustrates what happens to the wax on each rod after five minutes.
What can you conclude from the given diagram?
(i) The aluminium rod conducts heat better than the brass rod.
(ii) The aluminium rod conducts heat better than the copper rod.
(iii) The glass rod conducts heat better than the copper rod.
(iv) The wax on the copper rod melts faster than the wax on the brass rod.
By observing the amount of wax melted in each case in the figure, we can conclude about the conductivity of the rods. As the wax melted maximum on copper rod, it is a good conductor of heat followed by aluminium and brass. Glass is an insulator.
Study the given flowchart and identify the processes P, Q, R and S carried out in the given sequence for separation of the mixture.
Camphor being sublimable in nature, is separated by sublimation (process in which solid is directly converted into vapours on heating). Iron being magnetic in nature, is separated by magnetic separation method. Sand particles being large in size and insoluble in water are separated by filtration. They are obtained in the filter paper.
On evaporating the filtrate, salt is separated.
Properties of three substances X, Y and Z are given below : X : Heavy and non-magnetic Y : Light and non-magnetic Z : Magnetic If X, Y and Z are of same size and colour then, which of the following can be used to separate these particles from their mixture?
Heavier (X) particles and lighter (Y) particles are first separated by winnowing and then magnetic (Z) particles are separated from the remaining mixture by magnetic separation.
The table below shows the properties of four substances K, L, M and N.
Which two substances would be most difficult to separate when mixed in water?
Separation of K and M would be most difficult because both the substances are soluble in water, non-magnetic and have same colour.
The given flowchart was prepared by Natasha for sorting materials into different groups. She handed over the chart to her teacher with few blanks. Fill in the blanks from the given options.
A brief information about three substances is given : X: Transparent, smooth to touch and insulator. Y: Yellow in colour, good conductor of heat and electricity, lustrous. Z: Man made material, an insulator, used to make switches and handles of cooking utensils. X, Y and Z could be respectively.