1214 + Interview Questions in Chemistry in Class 8 Page 13 InterviewSolution

601.	Melting of ice into water is a
Answer» CHEMICAL CHANGE PHYSICAL change irreversible change periodic change Solution :physical change

Discussion

602.	............means the dissolving capacity of a solute in a solvent.
Answer» ANSWER :SOLUBILITY

Discussion

603.	Maximum number of valence electrons possible in an atom are
Answer» 5 6 7 8 Answer :D

Discussion

604.	Maximum number of electrons in an energy shell is given by the formula ........................ .
Answer» SOLUTION :`2N^(2)`

Discussion

605.	Matter with no fixed shape but definite volume exists in following state.
Answer» solid LIQUID gas gases SOLUTION :liquid

Discussion

606.	Match the following {:(,"Process",,"Type if reaction"),(1.,"Crumbling of chalk when heated","(a)","Single displacement"),(2.,"Iron displacing copper from copper sulphate","(b)","Decomposition"),(3.,"Formation of an insoluble compound","(c)","Exothermic"),(4.,"Energy released is more than the energy absorbed","(d)","Endothermic"),(5.,"Dissolution of ammonium chloride"(NH_(4)Cl)" in water","(e)","Precipitation"):}
Answer» ANSWER :B,a,E,C,d

Discussion

607.	Match the following
Answer» SOLUTION :1. B 2. a 3.d 4. C

Discussion

608.	Match the following
Answer» SOLUTION :1.c 2.a 3.d 4. B

Discussion

609.	Mass of total positive charge present in an atom is 16533 times to that of mass of electron. Find the atomic number of an element.
Answer» Solution :(i) COMPARISON of mass of ELECTRON and proton (II) CALCULATION of NUMBER of electrons.

Discussion

610.	Mass number of two isotopes of an element differ by 2 unit (A and A + 2) . Average atomic mass is 0.5 more than the lower mass number. What could be the ratio of the two isotopes.
Answer» Solution :(i) If the abundance of the ISOTOPE with MASS number A and A +2 are `n_(1) and n_(2)` respectively , then `(n_(1)A+n_(2)(A+2))/(n_(1)+n_(2))` =A+5 (II) `3:1`

Discussion

611.	Mass number is the sum of the number of protrons in an atom.
Answer» ANSWER :1

Discussion

612.	Mark the correct answer.Rayon is different from synthetic fibre because(a) it has a silk-like appearance.(b) it is obtained from wood pulp.(c) its fibres can also be woven like those of natural fibres.
Answer» ANSWER :it is OBTAINED from WOOD PULP.

Discussion

613.	Many theories and experiments carried out for the studey of atom eventually led to the development of its structure . Arrange the given theories or models of atom proposed by different scientists in chronological order. (a) Planetary model (b) Watermelon model (c) Bohr's atomic model (d) Dalton's atomic theory
Answer» c b a d d a b c b a d c d b a c Solution :The different models/theories proposed are arranged in a CHRONOLOGICAL order which LED to the DEVELOPMENT of modern structure of the ATOM. (i) Dalton's atomic theory (ii) Watermelon MODEL (iii) Planetary model (iv) Bohr's atomic model

Discussion

614.	Manufacturing synthetic fibres is actually helping conservation of forest'. Comment.
Answer» ANSWER :Manufacturing natural FIBRES is not eco-friendly because the main SOURCES of raw materials required for natural fibres are PLANTS or animal.

Discussion

615.	Make a model of a fire extinguisher. Place a short candle and a slightly taller candle in a small dish filled with baking soda. Place the dish at the bottom of a large bowl. Light both the candles. Then pour vinegar into the dish of baking soda. Take care. Do not pour vinegar on the candles. Observe the foaming reaction. What happens to the candles? Why? In what order?
Answer» Answer :We will observe that the Candle gets extinguished as the SUPPLY of oxygen is cut off DUE to THEPRODUCTION of foam.The smaller candle is effected by the foam prior to the LONGER candle, so it gets extinguishes first.

Discussion

616.	make a list of different kinds of plastic containers that you use in daily life.
Answer» Answer :the LIST of different kind of plastic containers used in daily LIFE are:(i) bottles(ii) tiffin BOX.

Discussion

617.	Make a list of items that can be recycled.
Answer» ANSWER :The following ITEMS can be recycled:(i) batteries(ii) books, MAGAZINES, NEWSPAPER ETC.

Discussion

618.	Magnesium reacts vigourously with hot water to form magnesium hydroxide.
Answer» ANSWER :F

Discussion

619.	Magnesium reacts vigorously with..................... and produces intense heat and forms magnesium oxide.
Answer» ANSWER :STEAM

Discussion

620.	Magnesium burns to form _________ prodicing heat and light.
Answer» ANSWER :A::D

Discussion

621.	M shell of two elements A and B have 18 electrons each. The difference in the number of electrons present in N shell of A and B is 8. M shell is the penultimate shell in B. Predict the range of probable atomic numbers of A and B.
Answer» Solution :As the penultimate SHELL of B is M shell which POSSESSES 18 ELECTRONS the valence shell should be N shell. The possible electronic configuration fo B ranges from 2,8,18, 1 to 2,8 , 18,8 The atomic numbers of B may range from Z=29 to Z =36. The electronic arrangement of A corresponding to the RESPECTIVE arrangement of B ranges from 2,8,18,9,2 to 2,8,18,16 , 2 . The atomic number of A may range from Z =39 to Z=46.

Discussion

622.	LPG stove can be lighted by using an automatic gas lighter. Is it possible to light a kerosne stove by using the same?
Answer» Solution :(i) Ignition TEMPERATURE. (ii) Conditions at which a FUEL can be BURNT. (iii) Comparison of these conditions to LPG and Kerosene. (iv) Temperature produced by automatic GAS lighter and the substance USED to light kerosene stove.

Discussion

623.	Low pressure is maintained in the dischargedue to
Answer» INCREASE the number of molecules increase ionisation of gas molecules decreaes the VELOCITY of the rays COMING from the cathode. All the above Answer :B::C

Discussion

624.	Look around and make a list of things made of polyester.
Answer» ANSWER :List of things made of polyester are:(i) FILMS,(II) CANOES,(iii) LCDs,(IV) holograms,(v) capacitors,(vii) insulating tapes,(viii) clothing/textile,(ix) ballons, etc.

Discussion

625.	List conditions under which combustion can take place.
Answer» ANSWER :Combustioh is a CHEMICAL PROCESS in which a substance UNDERGOES a reaction PRODUCING heat and light

Discussion

626.	Liquids which form separate layers when left undisturbed for sometime.
Answer» SOLUTION :IMMISCIBLE LIQUIDS

Discussion

627.	Liquid "___________" is used for preserving biological specimen
Answer» SOLUTION :NITROGEN

Discussion

628.	Is Lime juice in water is a homogeneous mixture.?
Answer» ANSWER :T

Discussion

629.	Liquid ________ is used to preservebiological specimens
Answer» ANSWER :`N_(2)`

Discussion

630.	Lithe physical pmperties of plastic sulphur.
Answer» Solution :Dark BROWN, AMORPHOUS, density is `1.92g//cm^3` INSOLUBLE in `CS_2`, bad conductor of HEART and electricity,B.P.`444^@`c, no SHARP M.P.

Discussion

631.	Lamp black is used as a filler in making rubber tyres.
Answer» ANSWER :TRUE

Discussion

632.	Label the following in the diagram. Different energy shells, valence shell, valence electrons
Answer» SOLUTION :

Discussion

633.	Label parts (a), (b), and (c) in the given figure.
Answer» SOLUTION :(a) Separating funnel (b) oil (C) WATER

Discussion

634.	Kinetic energy of molecules ……........ with decrease in temperature.
Answer» SOLUTION :DECREASE

Discussion

635.	Kerosene and water can be separated by filtration.
Answer» ANSWER :F

Discussion

636.	Isobars do notdiffer in the number of _______ .
Answer» SOLUTION :protons+neutrons

Discussion

637.	Is there a difference in the way metals and non-metals react with kids? What could the 'pop' sound in some cases be due to when a burning matchstick is brought near the mouth of the test tubes?
Answer» Answer :YES, metals react With acids producing hydrogen gas which BURNS with a 'pop' sound when a BURNING matchstick is brought near the MOUTH of the TEST tubes. Non-metals do not react with acids.

Discussion

638.	……..…….is the purest form of natural water.
Answer» ANSWER :RAINWATER

Discussion

639.	......................is soft and slippery with a basic pattern of hexagonal rings.
Answer» ANSWER :GRAPHITE

Discussion

640.	Is nylon fibre really so strong that we can make nylon parachutes and ropes for rock climbing?
Answer» Answer :Yes, nylon fibre is really so STRONG that we can MAKE nylon parachutes and ROPES for rock CLIMBING. Nylon fibre is elastic, LIGHT and stronger than even a steel wire.

Discussion

641.	Is it possible to perpare oxygen and hydrogen by the electrolysis of pure water? Give reasons in support of your answer. How are hydrogen and oxygen prepared in industry by the electrolysis of water?
Answer» Solution :Electrolysis of pure WATER cannot give OXYGEN and hydrogen since water is a POOR conductor. To make it an electrolytic conductor, some amount of acid should be added ot water which is CALLED acidulated water. ELECTOLYSIS of acidulated water gives hydrogen and oxygen at the respective electrodes.

Discussion

642.	Is it possible to dirnk by using a straw on the moon? Give reasons in support of your answer.
Answer» Solution :(i) Conditions for fluid to RISE up in straw. (II) Principle used in SUCKING a LIQUID through a straw. (iii) Conditions existing on moon. (iv) EFFECT of these conditions.

Discussion

643.	Iron rod is dipped in come HNO_3. Then it is made to react with copper sulphate solution. What observations are found in this process? Give reasons in support of your answer
Answer» SOLUTION :(i) Reactivity ofiron with `HNO_3`. (II) Reactivity of iron with `HNO_3`. (iii) PRODUCT OBTAINED. (iv) Reectivity of the product obtain

Discussion

644.	Iron possesses good casting properies when compared with copper because
Answer» iron CONTRACTS on solidification. iron expands on solidification. COPPER expands on solidification. Copper NEITHER contracts nor expands on solidification. Answer :B::C

Discussion

645.	Iron and rust have the same properties
Answer» ANSWER :F

Discussion

646.	Iodine can be separated from sand by sublimation.
Answer» ANSWER :T

Discussion

647.	Inter-particle force of attraction is weakest in gases.
Answer» ANSWER :T

Discussion

648.	Ink is a heterogeneous mixture.
Answer» ANSWER :F

Discussion

649.	Inflating a ballon is an irreversible change
Answer» ANSWER :F

Discussion

650.	Increase in temperature changes the solubility of a solution in the following way
Answer» SOLUBILITY DECREASES solubility INCREASES solubility REMAINS same increases solute Answer :B

Discussion

Explore topic-wise InterviewSolutions in .

Melting of ice into water is a

............means the dissolving capacity of a solute in a solvent.

Maximum number of valence electrons possible in an atom are

Maximum number of electrons in an energy shell is given by the formula ........................ .

Matter with no fixed shape but definite volume exists in following state.

Match the following

Match the following

Mass of total positive charge present in an atom is 16533 times to that of mass of electron. Find the atomic number of an element.

Mass number of two isotopes of an element differ by 2 unit (A and A + 2) . Average atomic mass is 0.5 more than the lower mass number. What could be the ratio of the two isotopes.

Mass number is the sum of the number of protrons in an atom.

Mark the correct answer.Rayon is different from synthetic fibre because(a) it has a silk-like appearance.(b) it is obtained from wood pulp.(c) its fibres can also be woven like those of natural fibres.

Manufacturing synthetic fibres is actually helping conservation of forest'. Comment.

make a list of different kinds of plastic containers that you use in daily life.

Make a list of items that can be recycled.

Magnesium reacts vigourously with hot water to form magnesium hydroxide.

Magnesium reacts vigorously with..................... and produces intense heat and forms magnesium oxide.

Magnesium burns to form _________ prodicing heat and light.

M shell of two elements A and B have 18 electrons each. The difference in the number of electrons present in N shell of A and B is 8. M shell is the penultimate shell in B. Predict the range of probable atomic numbers of A and B.

LPG stove can be lighted by using an automatic gas lighter. Is it possible to light a kerosne stove by using the same?

Low pressure is maintained in the dischargedue to

Look around and make a list of things made of polyester.

List conditions under which combustion can take place.

Liquids which form separate layers when left undisturbed for sometime.

Liquid "___________" is used for preserving biological specimen

Is Lime juice in water is a homogeneous mixture.?

Liquid ________ is used to preservebiological specimens

Lithe physical pmperties of plastic sulphur.

Lamp black is used as a filler in making rubber tyres.

Label the following in the diagram. Different energy shells, valence shell, valence electrons

Label parts (a), (b), and (c) in the given figure.

Kinetic energy of molecules ……........ with decrease in temperature.

Kerosene and water can be separated by filtration.

Isobars do notdiffer in the number of _______ .

Is there a difference in the way metals and non-metals react with kids? What could the 'pop' sound in some cases be due to when a burning matchstick is brought near the mouth of the test tubes?

……..…….is the purest form of natural water.

......................is soft and slippery with a basic pattern of hexagonal rings.

Is nylon fibre really so strong that we can make nylon parachutes and ropes for rock climbing?

Is it possible to perpare oxygen and hydrogen by the electrolysis of pure water? Give reasons in support of your answer. How are hydrogen and oxygen prepared in industry by the electrolysis of water?

Is it possible to dirnk by using a straw on the moon? Give reasons in support of your answer.

Iron rod is dipped in come HNO_3. Then it is made to react with copper sulphate solution. What observations are found in this process? Give reasons in support of your answer

Iron possesses good casting properies when compared with copper because

Iron and rust have the same properties

Iodine can be separated from sand by sublimation.

Inter-particle force of attraction is weakest in gases.

Ink is a heterogeneous mixture.

Inflating a ballon is an irreversible change

Increase in temperature changes the solubility of a solution in the following way