1214 + Interview Questions in Chemistry in Class 8 Page 20 InterviewSolution

951.	Discuss briefly the chemical properties of H_2S.
Answer» SOLUTION :(i) Acidic NATURE (ii) REDUCING nature (III) Reaction With potassium permanganate (iv) HCl formation

Discussion

952.	Discuss any two chemical properties of methane.
Answer» SOLUTION :COMBUSTION, CRACKING

Discussion

953.	Discharge doesn't take place at normal atmospheric pressure inside the cathode ray tube . Justify
Answer» SOLUTION :(i) Number of gaseous molecules present at HIGH PRESSURE. (ii) Effect of pressure on velocity of cathode rays (III) Relation between velocity and DISCHARGE

Discussion

954.	Differentiate the following (a) Evaporation and boiling (b) Gas and vapour (c ) Metals and non- metals (d) Pure substances and mixtures
Answer» SOLUTION :(i) Critical temperature (ii) PHYSICAL and CHEMICAL PROPERTIES (iii)Constituent particles

Discussion

955.	Differentiate between Slow and fast changes
Answer» SOLUTION :MELTING

Discussion

956.	Differentiate between Reversible and irreversible changes
Answer» SOLUTION :CURD MAKING and ROTTING

Discussion

957.	Differentiate between rhombic and monoclinic sulphur
Answer» Solution :(i) Other NAMES (ii) PREPARATION (iii) Colour (iv) Shape/su'uctum (v) DensitySolubility (vii) MELTING POINT (viii) Conductivity (ix) Boiling point

Discussion

958.	Differentiate between efflorescent and deliquescent substances.
Answer» SOLUTION :Hydrated crystals which lose its water of crystallization . The crystals which absorb MOISTURE and FORMS solution.

Discussion

959.	Differentiate between dilute and concentrated solutions.
Answer» Solution :The solution in which there is LESS AMOUNT of solute is the dilute SOLUTIONAND the solution in which there is a LARGE amount of solute is concentrated solutions

Discussion

960.	Different steps involved ind the mechanism of preparation of sodium hydoxide by Castner process are given bleow .Arrange them in correct sequence . (i)2Cl^(-)rarr Cl_2+2e^(-) ( b) Na_a Hg-2e^(-)rarr2Na^++Hg ( c) 2H_2O+2e^(-) rarr H_2+2OH (d ) Hg+2Na^+2bare rarr Na_2HG ( e)2NaClrarr2Na^+2Cl ( f) 2Na^(+)+2OH^(-)rarr2NaOH
Answer» E d C B a F e b c a d f d b a e c f e a d b c f SOLUTION :`2NaClrarr2Na^++2Cl^-` `2ClrarrCl_2+2e^-` `Hg+2Na^++2erarrNa_2Hg` `Na_2Hg-2erarr2Na^++Hg` `2H_2O+2erarrH_2+2OH^-` `2Na^++2OH^(-)rarr2NaOH`

Discussion

961.	Different steps involved in the manufacture of sulphuric acid in contact process are given below. Arrange them in the correct sequence Formation of oleum Oxidation of SO_2 , Hydrolysis of oleum Combustion of sulphur
Answer» d ac b a d b C d b a c a d c b Solution :(i) Combustion of SULPHUR (ii) OXIDATION of `SO_2` (iii) Formation of oleum (iv) HYDROLYSIS of oleum

Discussion

962.	Different processes involved in the manufactureo f pottery or ceramic materials are given below. Arrange them in a proper sequence. Change in the physical and chemical proerties of the substance Heating to a suitable high tempreture Drying of the mixture Prepartion of mixture by adding water to raw materials
Answer» B a d C d c b a d c a b c d b a Solution :(i) Preparation of mixture by adding WATER to raw MATERIALS. - (ii) Drying of the mixture. (iii) HEATING to a suitable high temperature. (iv) Change in the physical and chemical properties of the substances

Discussion

963.	Different gases can produced colours in discharge tube. Explain with reason.
Answer» SOLUTION :(i) Forces of attraction existing between protons and ELECTRONS (ii) Energy REQUIRED for excitation of electrons. (III) Relations between energy emitted by atom and colour of discharge tube.

Discussion

964.	Diamond is a good thermal conductor like metal. However it is a poor electrical conductor unlike metals. How do you account for this ?
Answer» Solution :(i) Requisite for a SUBSTANCE to be a good thermal and electical conductors. (ii) Comparison of arrangement of atoms in metal and diamond respectively. (iii) Effect of the above arrangement on the TERMAL conductivity. (iv) Reason behind the electrical conductivity in metals. (V) Number of ELECTRONS involved in BOND formation of carbon in diamond.

Discussion

965.	Diamond is hard and a bad conductor of electricity while graphite is soft and a good conductor of electricity. Explain. State the hybridization of carbon in both substances.
Answer» ANSWER :t

Discussion

966.	Devise an activity to show that organic waste is biodegradable while plastic is not.
Answer» ANSWER :An activity to SHOW that ORGANIC WASTE is biodegradable while plastic is not.

Discussion

967.	Desiccating material is used as dehumidifying agent for absorbing moisture from highly humid air and again it is made reusable by low humid air. What is the principle involved in this process ?
Answer» Solution :Disiccant materials have ahigh affinity for water vapour. The process involoves exposing the desiccant material to humid air stream, allowing it to ATTRACT and ratain some of the water vapour and then exposing the same desiccants to a dry air stream which has the effect of DRAWING the retained MOISTURE from the desiccant. The first air stream is the air that is being dehumidified while the SECOND air stream is USED only to regenerate the desiccant material.

Discussion

968.	Describe the structure of diamond.
Answer» Solution :(i) Number of carbons each carbons is bonded to . (II) TETRAHEDRAL arrangement . (iii) Rigid three DIMENSIONAL STRUCTURE.

Discussion

969.	Describe how sulphur is extracted using the Sicilian process.
Answer» Solution :(i) Existence/position of SULPHUR (II) Brick kilns, sloping hill sides (III) Small spaces (iv) POWDERED sulphur (v) MOLTEN sulphur

Discussion

970.	Describe a method of preparing carbon dioxide .
Answer» SOLUTION :`CaCO_(3)+2HCL to CaCl_(2)+H_(2)O+CO_(2)uarr`

Discussion

971.	Describe a laboratory method of the preparation of wood charcoal.
Answer» SOLUTION :HEATING WOOD SHAVINGS in the absene of AIR.

Discussion

972.	Derive the chemical formula of the following compounds. 1. Calcium oxide 2. Sodium chloride 3. Sulphuric acid 4. Iron sulphide 5. Water
Answer» SOLUTION :1. CaO 2. NaCl 3. `H_(2)SO_(4)` 4. FeS 5. `H_(2)O`

Discussion

973.	Define the following terms. (i) Melting or fusion (ii) Evaporation (iii) Condensation (iv) Solidification (v) Sublimation (vi) Melting Point (vii) Boiling Point (viii) Liquifaction (ix) Freezing Point (x) Critical Temperature (xi) Matter (xii) Pure Substance (xiii) Mixture (xiv) Element (xv) Compound (xvi) Metal (xvii) Non-metal (xviii) Metalloids (xix) Alloy (xx) Noble metals
Answer» Solution :(i) Solid to liquid state (ii) Liquid to vapour state (iii) Gas to liquid state (iv ) Liquid to solid state (v) Solid to vapour state (vi) (a) Temperature (b) Solid to liquid state (c ) PRESSURE conditions (vii) (a) Temperature (b) Liquid to vapour state (c ) Atmospheric pressure (viii) Pressure (ix) (a) Temperature (b) Liquid to solid state (c) Atmospheric pressure (X) Temperature above which a gas cannot be liquefied. (xi) Mass, occupies volume (xii) Homogenous, contains only one kind of particles. (xiii) MIXING of two more elements of compounds in any proportion. (xiv) Like atoms (XV) Like molecules (xvi) 1, 2, 3 valence electrons (xvii) 4, 5, 6, 7, 8 valence electrons (xviii) Properties of both metals and non metals (xix) Solid-solid homogenous mixture. (xx) chemically unreactive

Discussion

974.	Define malleability.
Answer» Answer :The PROPERTY by VIRTUE of which metals can be BEATEN into sheets is CALLED MALLEABILITY. For example, aluminium.

Discussion

975.	Define ignition temperature.
Answer» Answer : The CAPACITY of a substance to CATCH fire at the lowest TEMPERATURE is known as the IGNITION temperature.

Discussion

976.	Define glass blowing.What are the different methods employed for glass blowing
Answer» Solution :MANUFACTURE of diferent GLASS ARTICLES freeblowing, MOULD BLOWING

Discussion

977.	Define endothermic reaction. Give one example.
Answer» SOLUTION :ABSORPTION of HEAT ENERGY.

Discussion

978.	Define ductility.
Answer» ANSWER :Ductility is the property by VIRTUE of which a metal can be DRAWN into wires.For example,COPPER.

Discussion

979.	Define exotherrnic reaction. Give an example.
Answer» SOLUTION :RELEASE of HEAT ENERGY

Discussion

980.	Define atomic number and mass number. How can you represent an atom by using atomic number and mass number ? Give two examples.
Answer» SOLUTION :Z=no. of PROTONS , A=p+n

Discussion

981.	Define atmosphere.
Answer» Solution :The layer of AIR that surrounds the EARTH up to an altitude of 300 KM is called the ATMOSPHERE.

Discussion

982.	Define acid rain.
Answer» Answer :When the oxides of NITROGEN and sulphur dioxide dissolves in rainwater forming ACIDS and then REACHES the earth surface, it is KNOWN as ACID rain.

Discussion

983.	Deepa and her family on their house warming ceremony received many bouquets which they kept at the corner of drawing room. After some time, they felt the fragrance of the flowers all over the drawing room. What could be the reason behind this ? Explain with suitalble reasson.
Answer» SOLUTION :The molecules which CAUSE fragrance diffused into the air from the bouquets and that's how travel from ONE corner of the room to ANOTHER. So, DEEPA and her family after sometime felt the fragrance of the flowers all over the room.

Discussion

984.	Deep sea divers carry oxygen diluted by helium in cylinders instead of air. Give reasons.
Answer» Solution :In deep SEA the pressure is more than the normal atmospheric pressure. Solubility of a gas increases, with the increase in pressure. Normal air contain 20% oxygen. Due to increase in solubility in deep sea, only 4% oxygen is required. If `N_(2)` is used to dilute `O_(2)`, it ALSO dissolves in blood due to high pressure. When the diver COMES up the dissolved nitrogen, cscapes out in the FORM of bubbles which hinders the flow o blood. This caucses, painful scnsation called blond. The solubility of HELIUM is least among all the gases. Hence He is used for diluting `O_(2)`.

Discussion

985.	Decrease of pressure __________the boiling point of a liquid.
Answer» ANSWER :DECREASES

Discussion

986.	Decantation is a better method of separation than filtration.
Answer» ANSWER :F

Discussion

987.	Crystals can be made
Answer» by cooling hot saturated SOLUTION by evaporating UNSATURATED solution slowly by cooling a fused mass All of the above Solution :CRYSTALS can be made by following process (i) by cooling hot saturated solution (ii) by evaporating unsaturated solution slowly (iii) by cooling a fused mass

Discussion

988.	Crystallisation of carbon to form diamonds takes place when _____ metal expands during solidification.
Answer» ANSWER :IRON

Discussion

989.	Corbon dioxide from air is removed by passing air through _____.
Answer» CAUSTIC potash concentrated `H_(2)SO_(4)` anhydrous `CaCl_(2)` filters Solution :Carbon dioxide from AIR is removed by passing air through caustic potash.

Discussion

990.	Copper metal can displace magnesium sulphate to give copper sulphate and magnesium.
Answer» ANSWER :F

Discussion

991.	Copper in copper oxide does not liberate SO_(2) gas while copper in bronze cvolves SO_(2) gas with conc.H_(2)SO_(4). However, for making statues, copper is used in the form of bronze but not metallic copper or copper oxide. Explain why the same copper has such varied properties.
Answer» SOLUTION :(i) Composition of BRONZE. (ii) Comparison of chemical properties of constituents of bronze and CuO. (III) Comparison of physical properties of constituents of bronze with CuO and CU.

Discussion

992.	Cooling decreases the kinetic energy of particles.
Answer» ANSWER :T

Discussion

993.	Conduction of heat is not possible through gases. Explain using kinetic molecular theory.
Answer» Solution :(i) Conduction of heat takes place DUE to ordered vibratory MOTION of MOLECULES. (ii)The mode of the conduction of heat through a SUBSTANCE. (iii) The arrangement of molecules in gases. (iv) The EFFECT of this arrangement on the conduction of heat.

Discussion

994.	Concentrated HNO_3 and concentrated H_2SO_4 can t be used for the preparation of H_2S. Give reason
Answer» Solution :Both concentrated `HNO_3` and concented `H_2SO_4` are strong OXIDIZING agents. As a result they react with `H_2S` formed and oxidize it to sulphur .Here the ACIDS are reduced to `SO_2" and " NO_2` RESPECTIVELY . `H_2S+H_2SO_4rarr S+SO_2+H_2O` `H_2S+2HNO_3 RARR S+2CO_2H_2O`

Discussion

995.	Compound is a pure substance.
Answer» ANSWER :T

Discussion

996.	Name the compound formed by haemoglobin with carbon monoxide.
Answer» ANSWER :CARBAMINOHAEMOGLOBIN

Discussion

997.	Components of sand-iodine mixture can be separated by .............. process.
Answer» SOLUTION :SUBLIMATION

Discussion

998.	Components of a compound are present in a fixed composition.
Answer» ANSWER :T

Discussion

999.	Complete the following reactions of iron and magnesium with oxygen. Iron(Fe)+Oxygen(O_2)+Water(H_2O)rarr? Magnesium(Mg)+Oxygen(O_2)rarr?
Answer» ANSWER :`3Fe+O_2+2H_2O->Fe_3O_4+2H_2` `2Mg+O_2->2MgO`

Discussion

1000.	Compare the inter-particle space and forces of attraction between (a) and (b).
Answer» Solution :is solid, so it has NEGLIGIBLE inter-particle SPACE but strong inter-particle forces of attraction but (B) is LIQUID, so it has more inter-particle SPACES but less inter-particle forces of attraction.

Discussion

Explore topic-wise InterviewSolutions in .

Discuss briefly the chemical properties of H_2S.

Discuss any two chemical properties of methane.

Discharge doesn't take place at normal atmospheric pressure inside the cathode ray tube . Justify

Differentiate the following (a) Evaporation and boiling (b) Gas and vapour (c ) Metals and non- metals (d) Pure substances and mixtures

Differentiate between Slow and fast changes

Differentiate between Reversible and irreversible changes

Differentiate between rhombic and monoclinic sulphur

Differentiate between efflorescent and deliquescent substances.

Differentiate between dilute and concentrated solutions.

Different steps involved in the manufacture of sulphuric acid in contact process are given below. Arrange them in the correct sequence Formation of oleum Oxidation of SO_2 , Hydrolysis of oleum Combustion of sulphur

Different gases can produced colours in discharge tube. Explain with reason.

Diamond is a good thermal conductor like metal. However it is a poor electrical conductor unlike metals. How do you account for this ?

Diamond is hard and a bad conductor of electricity while graphite is soft and a good conductor of electricity. Explain. State the hybridization of carbon in both substances.

Devise an activity to show that organic waste is biodegradable while plastic is not.

Desiccating material is used as dehumidifying agent for absorbing moisture from highly humid air and again it is made reusable by low humid air. What is the principle involved in this process ?

Describe the structure of diamond.

Describe how sulphur is extracted using the Sicilian process.

Describe a method of preparing carbon dioxide .

Describe a laboratory method of the preparation of wood charcoal.

Derive the chemical formula of the following compounds. 1. Calcium oxide 2. Sodium chloride 3. Sulphuric acid 4. Iron sulphide 5. Water

Define malleability.

Define ignition temperature.

Define glass blowing.What are the different methods employed for glass blowing

Define endothermic reaction. Give one example.

Define ductility.

Define exotherrnic reaction. Give an example.

Define atomic number and mass number. How can you represent an atom by using atomic number and mass number ? Give two examples.

Define atmosphere.

Define acid rain.

Deepa and her family on their house warming ceremony received many bouquets which they kept at the corner of drawing room. After some time, they felt the fragrance of the flowers all over the drawing room. What could be the reason behind this ? Explain with suitalble reasson.

Deep sea divers carry oxygen diluted by helium in cylinders instead of air. Give reasons.

Decrease of pressure __________the boiling point of a liquid.

Decantation is a better method of separation than filtration.

Crystals can be made

Crystallisation of carbon to form diamonds takes place when _____ metal expands during solidification.

Corbon dioxide from air is removed by passing air through _____.

Copper metal can displace magnesium sulphate to give copper sulphate and magnesium.

Copper in copper oxide does not liberate SO_(2) gas while copper in bronze cvolves SO_(2) gas with conc.H_(2)SO_(4). However, for making statues, copper is used in the form of bronze but not metallic copper or copper oxide. Explain why the same copper has such varied properties.

Cooling decreases the kinetic energy of particles.

Conduction of heat is not possible through gases. Explain using kinetic molecular theory.

Concentrated HNO_3 and concentrated H_2SO_4 can t be used for the preparation of H_2S. Give reason

Compound is a pure substance.

Name the compound formed by haemoglobin with carbon monoxide.

Components of sand-iodine mixture can be separated by .............. process.

Components of a compound are present in a fixed composition.

Complete the following reactions of iron and magnesium with oxygen. Iron(Fe)+Oxygen(O_2)+Water(H_2O)rarr? Magnesium(Mg)+Oxygen(O_2)rarr?

Compare the inter-particle space and forces of attraction between (a) and (b).