1214 + Interview Questions in Chemistry in Class 8 Page 7 InterviewSolution

301.	What is a synthetic fibre?
Answer» Answer :Synthetic FIBRE is a substance formed by the CHEMICAL COMBINATION of a LARGE number of POLYMERS.

Discussion

302.	When perfume is poured on the palm, cooling sensation is perceived. Name and explain the phenomenon associated with it.
Answer» Solution :Perfume is HIGHLY volatile LIQUID. When it rapidly EVAPORATES from the Palm, it absorbs heat ENERGY from the palm. This gives a COOLING sensation.

Discussion

303.	Which of the following metals gives reddish powder on reaction with O_(2) higher temperature?
Answer» Fe Pb Zn Sn Solution :At higher temperature oxygen on reaction with iron gives REDDISH BROWN powder with crakling noise due to the FORMATION of ferric tetraoxide or ferrose ferric oxide `3Fe+2O_(2)toFe_(3)O_(4)` Reddish brown powder

Discussion

304.	What are the uses of neon and argon?
Answer» Solution :ADVERTISEMENT SIGN BOARDS, ELECTRIC BULBS.

Discussion

305.	Which among the following substance acts as a desiccating agent ?
Answer» ANHYDROUS calcium chloride Calcium oxide Hydrated COPPER sulphate Anhydrous sodium chloride Solution :Calcium oxide acts as a DESICCATING AGENT.

Discussion

306.	Though P_2O_5 is a very good desiccant, its utility for drying is limited. Give reasons
Answer» SOLUTION : `P_2O_5` is a very GOOD dehydratinga gent, but, is not used POPULARLY asadehydratinga gent,because, the water absorbed by this forms a protective viscous coating that inhibits further dehydration. However, granular FORM of `P_4O_10` can be used as a good dehydrating agent

Discussion

307.	What are fullerences ?
Answer» Solution :Crystalline ALLOTROPE of carbon, `C_(60),C_(70)` up to `C_(350)` with hexagonal and pentagonal rings with FOOTBALL structure.

Discussion

308.	Which among the pairs are separated by using the principle of dissolution in suitable solvent?
Answer» `SO_(2) and N_(2)O_(5),KOH` as solvent `SO_(2) and NO_(2),KOH` as solvent `SO_(2) and N_(2)O_(3), KOH` as solvent `SO_(2) and NO,KOH` as solvent Answer :C::D

Discussion

309.	When chlorine reacts With hot and concentrated caustic alkali XOH, one of the products,Y is formed by this reaction is used as an oicidiser in the match industry. Identify the compoundY and the element X.
Answer» SOLUTION :(i) Oxidizer in match industry. (II) Identification of a SUBSTANCE used in match stick which supplies `O_2`. (iii) Balanced chemical equation. (iv) Identification of Xfrom the balanced chemical equation

Discussion

310.	Two moist red roses are taken in two containers A and B into which anhydride of sulphurous acid and a greenish yellow coloured gas are passed respectively. What changes are observed With respect to two roses inA and B? How do you account for these changes?
Answer» Solution :(i) Identification of reason for DECOLOURIZATION of MEIST ROSES. Identification of the two gases. CHARACTERISTIC property of the above gases. The effect of characteristic property of the above gases on the colour ofroses. Effect of ATMOSPHERIC oxygen on revival of the colour of one of the roses

Discussion

311.	When and where was oil first discovered in india ?
Answer» ANSWER :OIL was DISCOVERED in INDIA in 1867 in makum, ASSAM.

Discussion

312.	What do you mean by chlorination?
Answer» ANSWER :The COMMONLY used CHEMICAL method for PURIFYING water is TERMED as chlorination.

Discussion

313.	What is the difference between surface water and underground water ?
Answer» SOLUTION :WATER AVAILABLE on the surface of earth and under the earth's surface respectively.

Discussion

314.	Which of the following substances is used in place of H_(2)SO_(4) in foam type fire extinguishers ?
Answer» Saponin Aluminium SULPHATE SODIUM CARBONATE Alcohol . Answer :B

Discussion

315.	Type of configuration that an element with 8 valence electrons is said to possess.
Answer» SOLUTION :OCTET CONFIGURATION

Discussion

316.	The steps involved in the manufacture of glass are given below. Arrahge them in the correct sequence Moderate colling Addition of cullet Formation of respective silicates Preparation of fine powder of raw materials Heating of cullet at about 1600K to 1700K
Answer» d b e c a d e b a c d e c b a d b c e a Solution :(i) Preparation of FINE powder of raw materials. (II) Preparation of cullct (III) Heating of cullet at about 1600K to 1700K. (iv) Formation of respective silicatee. (v) MODERATE cooling

Discussion

317.	What should be our mantra for saving water?
Answer» ANSWER :Our mantra for saving WATER should be REDUCE, reuse and recycle.

Discussion

318.	Why are metals used in electrical wires?
Answer» ANSWER :METALS can conduct electricity and so they are USED in electrical WIRES.

Discussion

319.	Which of the following reactions is associated with the formation of a mirror like surface near the cooler part of the test tube?
Answer» Heating of mercric oxide Heating of silver oxide Heating of tri-lead oxide Heating of lead dioxide Solution :Heating of MERCURIC oxide is associated with the formation of MIRROR like SURFACE near the cooler part of the TEST tube.

Discussion

320.	The vacuum present above the column in mercury barometer is called ______.
Answer» SOLUTION :toricellian VACUUM

Discussion

321.	What will happen if high pressure is applied to state (c)?
Answer» SOLUTION :STATE (c) is gas, it will CHANGE to state (b) which is LIQUID

Discussion

322.	Why are chemicals stored in plastic containers?
Answer» ANSWER :PLASTICS do not react with air and water and do not get corroded easily, so CHEMICALS are satored in plastic CONTAINERS.

Discussion

323.	What would happen ifpeople travel in a non-pressurized aeroplane?
Answer» Solution :(i) Pressure inside non-pressurized aeroplanes at higher altitudes. (II) COMPARISON of pressure inside and outside a human body at sea level. (iii) Comparison of pressure in a human body and non-pressurized aeroplane. (IV) Effect of DIFFERENCE in pressure.

Discussion

324.	The salt of an oxtacid of metal M contains two sulphur and six oxygen atoms. What will be the formula of the base formed by the metal and why?
Answer» Solution :(i) Negative radical in an oxyacid. (ii) IDENTIFICATION of the types of negative RADICALS FORMED from sulphur and oxygen. (III)Derivation of the formula of the salt (iv)Derivation of the formula of the base formed by the metal.

Discussion

325.	What is nitrolim? How is it obtaine
Answer» Solution :Nitrolim is MIXTURE of calcium cyanamid and GRAPHITE. OBTAINED by the reaction of nitrogen and calcium CARBIDE

Discussion

326.	What is fire extinguisher? Mentions its types.
Answer» Solution :Device used for PUTTING off FIRES. Soda ACID, FOAM TYPE.

Discussion

327.	When two substance A and B of same mass are heated under similar conditions number of free surfaces have been found to reduce to zero from one. If A maintains constancy in the temperature for a longer time than B during heating , then
Answer» LATENT HEAT of FUSION of A is more than that of B. latent heat of vapourisation of A is more than that of B latent heat of fusion of B is more than that of A. latent heat of vapourisation of B is more than that of A. Answer :B::C

Discussion

328.	What is the principle involved in using brine solution to remove the ice piled on roads in cold regions?
Answer» Solution :The ICE piled on roads in the COLD REGIONS is removed by melting process. For this process brine solution is used because this decreases the melting POINT of ice. THUS ice melts below `0^(@)C` and can be removed.

Discussion

329.	What is rapid combustion?
Answer» Answer :COMBUSTION which takes place at a high speed is known as a RAPID combustion.For example,burning matchstick NEAR a GAS stove.

Discussion

330.	What is meant by atmospheric pressure?
Answer» SOLUTION :DOWNWARD pressure EXERTED by air DUE to its weight.

Discussion

331.	The valence shell of an element of atomic number 35 is the_____ shell.
Answer» SOLUTION :4TH SHELL

Discussion

332.	Two containers contain two different liquids A and B . The mass of liquid A is half the mass of mass of liquid B. Both of them supplied for this purpose in the case of liquid 'A' is double that in the case of liquid 'B'. Find out the ratio of the specific heat of liquid A and liquid 'B'.
Answer» Solution :(i) Relation between SPECIFIC HEAT and heat REQUIRED to change the temperature of the substance. (II) RELATIONSHIP among heat energy , supplied specific heat, mass and change in temperature of a substance.

Discussion

333.	Whichof the following carbonates does not decompose to give CO_(2) ?
Answer» `NaHCO_(3)` `CaCO_(3)` `K_(2)CO_(3)` `ZnCO_(3)`. ANSWER :C

Discussion

334.	You have already performed an activity of burning natural and synthetic fibres.Take an artificial (synthetic) silk thread and a pure silk thread. Burn these threads carefully. Did you notice any difference in the smell while burning? Now, burn a woollen fibre carefully. Did it smell like burning of artificial silk of that of pure silk? Can you explain why?What did you observe?
Answer» ANSWER :YES, there is difference in the smell while burning an ARTIFICIAL (SYNTHETIC) silk THREAD and a pure silk thread.

Discussion

335.	What is plastic? Give an example.
Answer» Answer :Plastic is a synthetic POLYMER like the synthetic fibre which can be MOULDED into any shape in a molten state and BECOME HARD on cooling.

Discussion

336.	Which of the following loses its activity on storing for a long time ?
Answer» CHLORINE Hydrogen CHLORIDE Bleaching powder Sodium hydroxide Solution :CHOICE ( 3)

Discussion

337.	Which of the following statements is true regarding solids?
Answer» Solids are highly compressible. Solids diffuse rapidly. Solids possess low density. Solids possess many NUMBER of FREE surfaces. Solution :DUE to close packing of MOLECULES in solids they possess definite SHAPE due to which they have many number of free surfaces.

Discussion

338.	What is spontaneous combustion?
Answer» ANSWER :When a material suddenly bursts by itself into flames WITHOUT the application of an external source, it is called spontaneous combustion. For example, phosphorus BURNS . in air at ROOM temperature.

Discussion

339.	The reaction Fe + StoFeS represents _______
Answer» SOLUTION :COMBINATION, SYNTHESIS.

Discussion

340.	The reaction C + O_2 to CO, follows the law of conservation of mass.
Answer» ANSWER :FALSE

Discussion

341.	The reaction between perfectly dry hydrogen and chlorine take place in the presence of direct sunlight only by the addition of a few drops of water. In this process water behaves as a/an
Answer» catalyst solvent dehydrating agent effloresecent substance Solution :The reaction between perfectly dry hydrogen and chlorine TAKES place in the presence of DIRECT sunlight only by the addition of a few drops of WATER. In this PROCESS water BEHAVES as a catalyst.

Discussion

342.	The reactioin of sodium and potassium with humid air is violent and explosive. However, when these metals are kept in an air tight container having silica gel, no reaction has been observed. Give reason.
Answer» Solution :Silica GEL can absorb the moisture present in the air tightcontainer and thus air present in the container is FREE from the moisture . Metals Na, K can REACT with air only when the reaction is initiated with moisture . Therefore, when metals are kept in an air TIGHT container having silica gel, no reaction takes place since the air is ABSOLUTELY dry.

Discussion

343.	The ratio of the number of neutrons present in the two element X and Y is 5:7 and the ratio of mass numbers is 10:13. Element X attains stable octet configuration by losing two elements from the fourth shell. Calculate the number of proteins , electrons and neutrons present in X and Y.
Answer» Solution :Element X attains stability by loosing two electrons from `4^(th)` shell, it's atomic NUMBER is 20, element is calcium. `therefore` The mass number of Ca is 40. Let the mass number of Y is a. `therefore(40)/(a)=(10)/(13) implies a =52` `therefore ` Mass number of Y is 52. Number of neutrons in X is 40-20=20 Let the atomic number of Y be n. `therefore` The number of neutrons in Y be 52-b `therefore(20)/(52-b)=(5)/(7)implies 52-b=28implies b=24` `therefore ` Element Y atomic number is 24 and number of neutrons in Y are 28

Discussion

344.	The ratio of number of electrons in N shell of A and M shell of B atomic numbers 40 and 32 respectively is
Answer» `5:3` `9:5` `5:9` `5:4` ANSWER :C

Discussion

345.	The ratio of KClO_(3)andMnO_(2) taken for the preparation oxygen is
Answer» `4:1` `3:1` `2:1` `2:5` Solution :4 PARTS of `KClO_(3)` and 1 part of `MnO_(2)` on heating GIVES oxygen gas.

Discussion

346.	The property of metals by which they can be beaten into thin sheets is called malleability. This is a characteristic property of metals. As you must have noticed, materials like coal and pencil lead do not show this property. Can we call these metals?
Answer» Answer :No, we cannot call MATERIALS LIKE COAL and pencil LEAD as metals.

Discussion

347.	The process of phase transition from solid to liquid involves the following steps. Arrange them in a proper sequence. (a) Molecules become free to move and thus attain molecular arrangement of liquid. (b) The energy supplied makes the molecules to vibrate more. (c ) During melting, the molecules overcome the forces of attraction between them. (d) the molecules acquire rotatory motion, translatory motion in additionto vibratory motion.
Answer» c d a b b c d a c d b a None of these Solution :(i) The ENERGY SUPPLIED makes the molecules to vibrate with more speed. (ii) During melting, the molecules overcome the forces of ATTRACTION between them. (iii) The molecules ACQUIRE rotatory motion, TRANSLATORY motion in addition to vibratory motion. (iv) Moleculesbecome free to move and thus attain the molecular arrangement of a liquid.

Discussion

348.	The process of glazing of ceramic article does not
Answer» MAKE it IMPERVIOUS impartglossy appearance make it IMPACT resistant All the above SOLUTION :Choice (3)

Discussion

349.	The process due to which some solid substance directly vaporise on heating and solidify on cooling, without becoming a liquid is called ________ .
Answer» SOLUTION :SUBLIMATION

Discussion

350.	The polymer 'cotton' is made from ______
Answer» ANSWER :B

Discussion

Explore topic-wise InterviewSolutions in .

What is a synthetic fibre?

When perfume is poured on the palm, cooling sensation is perceived. Name and explain the phenomenon associated with it.

Which of the following metals gives reddish powder on reaction with O_(2) higher temperature?

What are the uses of neon and argon?

Which among the following substance acts as a desiccating agent ?

Though P_2O_5 is a very good desiccant, its utility for drying is limited. Give reasons

What are fullerences ?

Which among the pairs are separated by using the principle of dissolution in suitable solvent?

When chlorine reacts With hot and concentrated caustic alkali XOH, one of the products,Y is formed by this reaction is used as an oicidiser in the match industry. Identify the compoundY and the element X.

Two moist red roses are taken in two containers A and B into which anhydride of sulphurous acid and a greenish yellow coloured gas are passed respectively. What changes are observed With respect to two roses inA and B? How do you account for these changes?

When and where was oil first discovered in india ?

What do you mean by chlorination?

What is the difference between surface water and underground water ?

Which of the following substances is used in place of H_(2)SO_(4) in foam type fire extinguishers ?

Type of configuration that an element with 8 valence electrons is said to possess.

The steps involved in the manufacture of glass are given below. Arrahge them in the correct sequence Moderate colling Addition of cullet Formation of respective silicates Preparation of fine powder of raw materials Heating of cullet at about 1600K to 1700K

What should be our mantra for saving water?

Why are metals used in electrical wires?

Which of the following reactions is associated with the formation of a mirror like surface near the cooler part of the test tube?

The vacuum present above the column in mercury barometer is called ______.

What will happen if high pressure is applied to state (c)?

Why are chemicals stored in plastic containers?

What would happen ifpeople travel in a non-pressurized aeroplane?

The salt of an oxtacid of metal M contains two sulphur and six oxygen atoms. What will be the formula of the base formed by the metal and why?

What is nitrolim? How is it obtaine

What is fire extinguisher? Mentions its types.

When two substance A and B of same mass are heated under similar conditions number of free surfaces have been found to reduce to zero from one. If A maintains constancy in the temperature for a longer time than B during heating , then

What is the principle involved in using brine solution to remove the ice piled on roads in cold regions?

What is rapid combustion?

What is meant by atmospheric pressure?

The valence shell of an element of atomic number 35 is the_____ shell.

Two containers contain two different liquids A and B . The mass of liquid A is half the mass of mass of liquid B. Both of them supplied for this purpose in the case of liquid 'A' is double that in the case of liquid 'B'. Find out the ratio of the specific heat of liquid A and liquid 'B'.

Whichof the following carbonates does not decompose to give CO_(2) ?

What is plastic? Give an example.

Which of the following loses its activity on storing for a long time ?

Which of the following statements is true regarding solids?

What is spontaneous combustion?

The reaction Fe + StoFeS represents _______

The reaction C + O_2 to CO, follows the law of conservation of mass.

The reaction between perfectly dry hydrogen and chlorine take place in the presence of direct sunlight only by the addition of a few drops of water. In this process water behaves as a/an

The reactioin of sodium and potassium with humid air is violent and explosive. However, when these metals are kept in an air tight container having silica gel, no reaction has been observed. Give reason.

The ratio of the number of neutrons present in the two element X and Y is 5:7 and the ratio of mass numbers is 10:13. Element X attains stable octet configuration by losing two elements from the fourth shell. Calculate the number of proteins , electrons and neutrons present in X and Y.

The ratio of number of electrons in N shell of A and M shell of B atomic numbers 40 and 32 respectively is

The ratio of KClO_(3)andMnO_(2) taken for the preparation oxygen is

The property of metals by which they can be beaten into thin sheets is called malleability. This is a characteristic property of metals. As you must have noticed, materials like coal and pencil lead do not show this property. Can we call these metals?

The process of glazing of ceramic article does not

The process due to which some solid substance directly vaporise on heating and solidify on cooling, without becoming a liquid is called ________ .

The polymer 'cotton' is made from ______