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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Calculate the strength of a solution containing 5 g of glucose in 200 mL of the solution. |
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Answer» Strength of solution = `("Mass of solute")/("Volume of solution in litres")` Mass of glucose = 5 g Volume of solution = 200 mL = `(200)/(1000) = 0.2 L` Strength of solution = `(5 g)/(0.2L) = 25 g//L` |
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| 52. |
What mass of sodium hydroxide must be dissovled in 500 mL of solution so that the strength of the solution may be 10 g/L ? |
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Answer» Strength of solution = `("Mass of solute")/("Volume of solution in litres")` Strength of solution = 10 g/L = `10 gL^(-1)` Volume of solution = 500 mL = 0.5 L `therefore` Mass of NaOH (solute) = `(10 gL^(-1)) xx (0.5 L) = 5 g` |
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| 53. |
While diluting a solution of salt in water, a student by mistake added acetone (boiling point `56(@)C`). What technique can be employed to get back acetone ? Justify your choice. |
| Answer» Acetone can be recovered by carrying out the distillation is a distillation flask. Its vapours will rise since it is volatile, get condensed and collected in a receiver. Salt being non-volatile in nature remains in the flask. | |
| 54. |
The technique which is used to separte paricles of a solid suspended in a liquid quickly is called :A. decanationB. centrifugationC. sedimentationD. filtration |
| Answer» Correct Answer - (b) | |
| 55. |
The material which is added to water during purification process at the water works so as to disinfect it is:A. postassium permanganateB. betadineC. chlorineD. potast alum |
| Answer» Correct Answer - (c ) | |
| 56. |
The correct increasing order of the boiling points of liquid oxygen, liwid argon and liquid nitrogen present in liquid air is:A. nitrogen, oxygen, argonB. nitrogen, argon, oxygenC. argon, oxygen, nitrogenD. oxygen, argon, nitrogen |
| Answer» Correct Answer - (b) | |
| 57. |
which one of the following is not a chemical change ?A. formation of curdB. ripening of bananaC. sublimation of napthaleneD. corrosion of photo frame |
| Answer» Correct Answer - ( C) | |
| 58. |
The liquid air has three components X,Y and Z whose boiling points are : `-186^(@)C,-183^(@)Cand -196^(@)C,` respectively. When liquid air is fed into a tall feactional distillation column from near its bottom and warmed up slowly: (a) Which component will be collected from near the bottom of the fraction distillation column ? Why ? (b) Which componnent will be collected from the top part of the fractional distillation column? Why ? (c) Which component will be collected from the middle part of the fractional distillation column? Why ? (d) What could the component X, Y and Z be |
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Answer» Correct Answer - (a) Y ; It has the highest boiling point of, `-183^(@)C` (b) Z; It has the lowest boiling point of, `-196^(@)C` (c ) X; It has a boiling point of, `-186^(@)C` which is lower than that of Y but higher than that of Z (d) X is liquid argon ; Y is liquid oxygen ;Z is liquid nitrigen |
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| 59. |
A solid mixture contains four consituents P, Q, and S.P consists of tiny graing and it is mixed with cement for plastering the walls. Q is a white solid which is recovered on a large scale from sea water by the process of evaporation. R is in the from of tiny particles of a material whose corrosion is called resting. And S is a white solid which is used in mking ordinary dry cells. (a) What could P, Q R and S be ? (b) How would you separte a mixture containing P, Q, R and S ? |
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Answer» Correct Answer - (a) P is sand ; Q is common salt ;R is iron filings ; S is ammonium chloride (b) First separate R (iron filings) by using a magnet to attract them. Then separte ammonium chloride by sublimation. Shake sand and common salt with water and filter. Sand obtained as residue. Evaporate filtrate to dryness to obtain common salt |
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| 60. |
Name the technique to separate (i) butter from curd (ii) salt from sea water (iii) camphor from salt. |
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Answer» (i) The separation can be done by carrying centrifugation in a centrifugal machine. (ii) The separation can be done either by crystallisation or by evaporation. (iii) The process of sublimation helps in separating camphor from salt. Camphor undergoes sublimation. |
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| 61. |
one of the following liquids will leave hbehind a residue on heating this one is :A. brineB. bromineC. mercuryD. alcohol |
| Answer» Correct Answer - (a) | |
| 62. |
There are three liquids A, B and C all having different densities and different boiling points. Liquids A and C are organic in nature wheres liquid B is considered yo be inorganic when liquids A and B are put together in a container, they form a single layer. On the other hand, when, liquids B and C are mixid, they form two separte layers: (a) Which process will you use to separte a mixture of A and B (b)Which method will you use to separate a mixture of B and C (c) Name the liquids which would behave like (i) A (ii) B and (iii) C. |
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Answer» Correct Answer - (a) Fractional distillaction (b) Separating funnel (c ) (i) Alcohol (ii) Water (iii) Oil |
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| 63. |
Some solids dissolve easily in liquids while the others donot (a) What is the name given to the liquids which dissolve in a liquid ? (c ) What is the name given to the liquid which contains in it some suspended particles ? |
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Answer» (a) The liquids are known as solvents (b) The clear liquid is called solution or true solution. (c ) The liquid is known as dispersion medium or dispersing medium. |
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| 64. |
which of the following does not a fixed melting point/ boiling point?A. goldB. ethanolC. airD. oxygen |
| Answer» Correct Answer - ( c) | |
| 65. |
A mixture of milk and groundnut oil can be separated by:A. sublimationB. evaporationC. separating funnelD. filtration |
| Answer» Correct Answer - (c ) | |
| 66. |
milk of following can be called a suspemsion ?A. milkB. milk of magnesiaC. salt solutionD. vinegar |
| Answer» Correct Answer - (b) | |
| 67. |
one of the following is a solids foam , this one is :A. butterB. breadC. shaving creamD. ruby |
| Answer» Correct Answer - (b) | |
| 68. |
Give some examples of Tyndall effect observed in your surroundings? |
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Answer» (i) Tyndall effect can be observed when sun light is made to enter the room in the morning time through a small slit. Dust particles with zig-zag motion can be seen. (ii) Tyndall effect can be seen when sun light passes through the canopy of a dense forest. |
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| 69. |
Milk of magnsia is :A. a colloidB. a true solutionC. a homogeneous mixtureD. a suspension |
| Answer» Correct Answer - (d) | |
| 70. |
what of the following is not an emulsion ?A. milkB. butterC. face creamD. shaving cream |
| Answer» Correct Answer - (d) | |
| 71. |
which one of the following is most likely to exhibit tyndall effect ?A. sugar and water mixtureB. potash alum and water mixtureC. chalk powder and water mixtureD. potassium permanganate and water mixture |
| Answer» Correct Answer - ( c) | |
| 72. |
one of the following does not show tyndall effect this one is :A. soap solutionB. inkC. sugar solutionD. starch solution |
| Answer» Correct Answer - (d) | |
| 73. |
(a) Colloidal solutions show Tyndall effect but true solutions do not. Discuss. (b) Explain how does soap help in cleaning dirty clothes ? |
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Answer» (a) In a colloidal solution, the particle size is such (1 nm to 100 nm), that these particles scatter the light rays as they fall on them. Because of scattering, the path of the light as well as the particles become visible. But in a true solution, the particle size is so small (less than 1nm) that these particles are not in a position to scatter the light. Therefore, true solution does not show any Tyndall effect. (b) In dirty clothes, the dust particles are sticking on the oil drops present. Simple water cannot remove these oil drops from the clothes because water and oil as such do not form a stable emulsion. Soap plays the role of emulsifier and helps in forming a stable emulsion between the two. In other words, it helps in mixing oil and water. This means that soap helps in removing these oil drops along with the dirt sticking to them. The dirty clothes get washed by soap solution. |
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| 74. |
Explain why , water is a compound and not a mxture . |
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Answer» Water is considered a compound because of the following reasons : (i) Water cannot be separated into its constituents , hydrogen and oxygen , by the physical methods (such as filtration , evaporation , distillation , sublimation , magnet , etc). (ii) the properties of water are entirely diffferent from those of its constituents , hydrogen and oxygen , for example , water is a liquid whereas hydrogen and oxygen are gases , water does not burn whereas hydrogen burns ,water does not suopport combustion whereas supports combustion . (iii) Heat and light are given out when water is prepared by by burning hydrogen in oxygen . (iv) the compostion of water is fixed , It contains hydrogen and oxygen combined togehter in a fixed proportion of 1:8 by mass, It has a definite formula ,`H_(2)O` (v) Water has a fixed boiling point of `100^(@)` C under standard almooshe3ric pressure. |
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| 75. |
Explain why , air is considered a mixture and not a compound. |
| Answer» Air is a homogeneous mixture of different gases which can be separated by suitable methods. Therefore, it is a mixture and not a compound. | |
| 76. |
Differentiate between an element and a compound. Categorise the following substances into elements and compounds. Sodium chloride, iodine, water, 24 carat gold, oxygen gas, carbon. |
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Answer» For distinction between element and compound. Elements : Iodine, 24 carat gold, carbon. Compounds : Sodium chloride, water, oxygen gas. |
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| 77. |
Give one example each of a mixture which shows the following characteristics. (a) A mixture of two volatile component. (b) A mixture of two volatile components with a boiling point difference less than 25 K. (c ) A mixture of a volatile and a non-volatile component. |
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Answer» (a) Iodine and camphor (b) Acetone (b.p. = 319 K) and ethyl alcohol (b.p. = 341K) (c ) Naphthalene and sodium chloride. |
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| 78. |
List two differences between a pure substance and a mixture. Give an example of each. |
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Answer» (i) A pure substances between or compound in completely pure state while mixture may contain two or more elements/compounds. (ii) Constituents from a mixture can be separated while pure substance remains as a single substance. Example : Copper (pure substance), Air (Mixture). |
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| 79. |
Give two differences between pure substances and mixture. Give one example of each. |
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Answer» (i) A pure substance is always a single substance (element or compound). A mixture has two or more constituents. (ii) A pure substance has always sharp melting or boiling point. A mixture does not have sharp melting or boiling point. Examples : Copper sulphate (Pure substance), Air (Mixture) |
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| 80. |
A solution contains 50 g of sugar in 450 g of water. Calculate the concentration in terms of mass by mass percentages of the solution. |
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Answer» Mass percent of sugar = `("Mass of sugar")/("Mass of solution")xx 100` `((50 g))/((500 g)) xx 100 = 10%` Mass percent of water = 100 - 10 = 90% |
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| 81. |
A solution contains 60 g of sugar in 480 g of water. Calculate the concentration of solution in terms of mass by mass percentage of the solution. |
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Answer» Mass of sugar (solute) = 60 g Mass of solvent (water) = 480 g Mass of solution = (60 + 480) = 540 g Concentration in term of mass percentage = `("Mass of solute")/("Mass of solution")xx 100 = ((60 g))/((540 g)) xx 100 = 11.1%` |
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| 82. |
(i) Name the separation technique used to separate the constituents of the mixture of miscible liquids. Draw a labelled diagram of the process for separating mixture of acetone and water. (ii) List two properties of the mixture of miscible liquids essential for the process. (iii) A simple fractionating column is provided with beads. Give reasons. |
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Answer» (i) The separation technique depends upon the boiling temperature difference between the miscible liquids. If they differ in their boiling points by `25^(@)C` or more, the separation can be done by simple distillation. If the difference is less than `25^(@)C`, fractional distillation is used. Acetone (b.p. = `56^(@C`) and water (b.p. = `100^(@)C`) can be separated by simple distillation. (ii) The constituents of the miscible liquids should be volatile in nature. The constituents of the miscible liquids should not react chemically with each other. (iii) The purpose of beads in the fractionating column is to obstruct the upward movement of liquid with higher boiling point. This helps in the separation of the two liquids. |
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| 83. |
Fractional distillation is suitable for separation of miscible liquids with a boiling point difference of about 25 K or less. What part of fractional distillation apparatus makes it efficient and possesses an advantages over a simple distillation process. Explain using a diagram. |
| Answer» It is the fractionating column which fits into the distillation flask. It is packed with a number of glass beads. As the vapours of both the volatile liquids rise upwards in the distillation flask, the beads obstruct their movement i.e. it slows down. The vapours of higher boiling liquid condense to the liquid state and in doing so they release certain energy known as latent heat of condensation. The energy which is released is taken up by the molecules of lower boiling liquid. As a result, they vapourise more quickly and pass through the water condenser and condense as a liquid in the receiver. The higher boiling liquid remains in the distillation flask only. For further details about the fractional distillation. | |
| 84. |
Can physical and chemical changes occur together ? Illustrate your answer. |
| Answer» It is illustrated by burning of candle. | |
| 85. |
The dyes present in fountain pen ink can be separted by the the process of:A. fractional distillationB. infrared photographyC. crystallisationD. chromatography |
| Answer» Correct Answer - (d) | |
| 86. |
Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures. (a) A volatile and a non-volatile component. (b) Two volatile components with appreciable difference in boiling points. (c) Two immiscible liquids. (d) One of the components changes directly from solid to gaseous state. (e) Two or more coloured constituents soluble in some solvent. |
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Answer» (a) Sulphur (a yellow solid) and iodine (a violet crystalline solid) are both soluble in carbon disulphide `(CS_(2))` solvent. Separation can be done by sublimation. Iodine sublimes on heating while sulphur does not. (b) Turpentine oil and water. Separation can be done with a separating funnel. (c ) Ammonium chloride and common salt. Ammonium chloride directly changes to vapour state (sublimes). |
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| 87. |
Two chemical species X and Y combine together to form a product P which contains both X and Y `X + Y rarr P` X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concering the species X, Y and P are correct ? (i) P is a compound (ii) X and Y are compounds (iii) X and Y are elements (iv) P has a fixed compositionA. (i), (ii) and (iii)B. (i), (ii) and (iv)C. (ii), (iii) and (iv)D. (i), (iii) and (iv). |
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Answer» Correct Answer - D All these statements are correct. |
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| 88. |
Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures (a) A volatile and a non-volatile components. (b) Two volatile components with appreciable difference in boiling points. (c ) Two immiscible liquids. (d) One of the components changes directly from solid to gaseous state. (e) Two or more coloured constituents soluble in same solvent. |
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Answer» (a) A mixture of naphthalene (volatile) and common salt (non-volatile). The separation can be done by sublimation. (b) A mixture of acetone boiling point = `56^(@)C`) and water (boiling point = `100^(@)C`) separation can be done by distillation. (c ) A mixture of kerosene oil and water. Separation can be done in a separating funnel. (d) Same as in (a) (e) A mixture of blue/black ink. Separation can be done by chromatography. |
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| 89. |
Salt can be recovered form its solution by evaporation. Suggest some other technique for the same ? |
| Answer» Crystallisation technique can also be used. For example, both these can be used to separate salts like sodium chloride (common salt) and potasium nitrate (nitre) from their aqueous solution. | |
| 90. |
Sugget a suitable separation technique for the following : (a) Mercury and water. (b) Coloured components from blue ink, (c ) Ammonium chloride and potassium chloride (d) Mixture of alcohol and water. |
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Answer» (a) The separation can be done by the use of separating funnel. Mercury forms the lower layer (heavier) and water the upper layer (lighter). (b) The separation can be done with the help of chromatography. (c ) Process of fractional distillation can be used. Alcohol (ethyl alcohol) with lower boiling point (`78^(@)C` or 351 K) gets distilled leaving behind water with higher boiling point (`100^(@)C` or 373 K) in the distillation flask. |
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| 91. |
Based on separation techniques, complete the following. The first one is done for you. `{:(,"Mixture","Type","Separation","Principle"),(,,,"Technique",),(1.,"Alcohol + water","Homogeneous","Frictional","Difference in"),(,,,"distillation","boiling point"),(2.,"Sulphur + carbon disulphide",-,-,-),(3.,"Sand + water",-,-,-),(4.,"Pigments of flower",-,-,-):}` |
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Answer» 2. Homogeneous, Evaporation, Difference in nature. 3. Hetereogeneous, Filtration, Difference in solubility in water 4. Homogeneous, Chromatography, Difference in adsorption of different components. |
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| 92. |
Suggest separation technique(s) one would need to employ to separate the following mixtures. (a) Mercury and water (b) Potassium chloride and ammonium chloride (c ) Common salt, water and sand (d) Kerosene oil, water and salt. |
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Answer» (a) Separation can be done with a separating funnel. Mercury being heavy forms lower layer. (b) Sublimation can be used. Ammonium chloride sublimes. (c ) Filtration followed by crystallisation techniques can be used here. Sand can be removed as an insoluble residue upon filtration. Upon evaporating the filtrate in a china dish to about one third followed by slow colling crystals of common salt (NaCl) are formed. (d) Kerosene oil can be separated with a separating funnel. What and salt can be separated either by distillation (water distils) or by evaporation (water evaporates). Salt is left behind as residue. |
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| 93. |
Classify each of the following as a homogeneous or heterogeneous mixture: soda water, wood air, soil, vinegar, filtered tea |
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Answer» Homogeneous mixture : Soda water, air, vinegar, Filtered tea. Heterogeneous mixture : Wood, soil. Air is a homogeneous mixture of different gases. However, if some dust or other particles are present, then air becomes a heterogeneous mixture. |
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| 94. |
Which separation techniques will you apply for the separation of the following ? (a) Sodium chloride from its solution in water. (b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride. (c ) Small pieces of metal in the engine oil of a car. (d) Different pigments from an extract of flower petals. (e ) Butter from curd. (f) Oil from tea. (g) Tea leaves from tea. (h) Iron pins from sand. (i) Wheat grains from husk. (j) Fine mud particles suspended in water. |
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Answer» (A) Evaporation : Water will evaporate leaving behind sodium chloride. (b) Sublimation : Ammonium chloride will be collected as sublimate. (c ) Filtration : Pieces of metal can be separated by filtration. (d) Chromatography : Pigments (coloured components) from the extract of flower plants can be separated by chromatography. (e) Centrifugation : Butter will get separated upon centrifugation. (f) Separating funnel : Oil and water can be separated by the use of separating funnel. (g) Filtration : Upon filtration through a sieve, tea leaves will be collected on the sieve. (h) Magnetic separation : A magnet will attract iron pins and not sand particles. (i) Sieving : Wheat grains from husk can be separated with the help of sieve. (f) Sedimentation : As a result of sedimentation, mud particles will settle as precipitate. It can be separated later on by filtration. |
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| 95. |
Which of the following are physical changes ? (i) Melting of iron metal (ii) Rusting of iron (iii) Bending of an iron rod (iv) Drawing a wire of iron metalA. (i), (ii) and (iii)B. (i), (ii) and (iv)C. (i), (iii) and (iv)D. (ii), (iii) and (iv). |
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Answer» Correct Answer - C All the three are examples of physical changes. |
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| 96. |
What is dispersed phase and dispersion medium in a colloid ? |
| Answer» If a colloidal solution is compared to an ordinary solution, then dispersed phase is comparable to the solute and dispersion medium to the solvent. | |