1214 + Interview Questions in Chemistry in Class 8 Page 14 InterviewSolution

651.	Incomplete burning of fuels produces carbon monoxide.
Answer» ANSWER :t

Discussion

652.	In winter mornings , the exhaled air turns foggy. Explain.
Answer» SOLUTION :(i) The contituents in the exhaled AIR. (ii) Comparison of the temperature of exhaled air with SURROUNDINGS. (iii) CHANGES in constituents of exhaled air with temperature.

Discussion

653.	In which way in water useful for generating electricity ?
Answer» SOLUTION :PHYSICAL STATE of WATER

Discussion

654.	In which of the following uses of nitrogen, its characteristic property of insert nature is not exploited?
Answer» It is used to preserve biological specimen. It DILUTES the activity of oxygen present in the atmosphere. It is used to preserve food materials. NITROGEN is used for the synthesis of AMMONIA. Solution :Nitrogen REACTS with hydrogen to form ammonia. Its inert nature is not used for this process.

Discussion

655.	In which of the following subtances, intermolecular force of attraction is the maximum?
Answer» IRON BAR Water Air Nitrogen Solution :Iron bar is solid and HENCE intermolecular force of ATTRACTION is MAXIMUM.

Discussion

656.	In what forms does sulphur occur in the combined state in nature?
Answer» SOLUTION : SULPHIDES, SULPHATES and in ORGANIC MATTER

Discussion

657.	In Thomson's atomic model, positive mass occupies more space than the negative charge in an atom.
Answer» ANSWER :TRUE

Discussion

658.	In the welding of railway tracks, a proper proportion of aluminium powder and iron (iii) oxide are made to react with each other at high temperature. Explain the type of reaction involved and also identify the reducing and the oxidizing agents.
Answer» Solution :(i)Given the formula of iron (III)oxide. (ii)Reaction betweenAl and iron (III) oxede. (iii) Based on the above chemical reaction, PREDICT the type of reactions. (IV)Identification of OXIDIZING and REDUCING agents.

Discussion

659.	In the welding of railvvay tracks, a proper proportion of aluminium powder and iron (III) oxide arc made to react with each other at high temperature. Explain the type of reaction involved and also identify the reducing and the oxidizing agents.
Answer» SOLUTION :At high temperature aluminium reacts with iron (III) oxide. `2Al+Fe_2O_3toAl_2O_3+2Fe+"HEAT"` It is a displacement and exothermic reaction. Al ACTS as reducing AGENT as it undergoes oxidation while `Fe_2O_3` acts as oxidizing agent as it undergoes reduction.

Discussion

660.	In the manufacture of silicon carbide by Acheson process, sawdust is used along with sand and coke in the electric furnance. What is the main purpose of using sawdust as one of the constituents of the mixture ?
Answer» Solution :Saw DUST used in the charge INCREASE its porosity. The increase in porosity allows a continuous escape of CARBON monoxide , that BURNS at the top of the charge. It also prevents heat loss.

Discussion

661.	In the manufacture of graphite by Acheson process, the chargefilled between the cathode and anode consist of
Answer» powdered coke, sand and ferric oxide powdered coke sand ferric oxide Solution :In the manufacture of GRAPHITE by Acheson PROCESS, the charge filled between the CATHODE and anode consist of powdered coke, sand and ferric oxide.

Discussion

662.	In the laboratory preparation of carbon dioxide, carbon dioxide is collected by:
Answer» DOWNWARD DISPLACEMENT of water upward displacement of water downward displacement of air upward displacement of air Answer :D

Discussion

663.	In spite of supplying heat, the temperature of the melting solid does not change. Explain with reasons.
Answer» Solution :(i) ATTHE melting POINT, molecules of a solid move apart. (ii) Different ENERGIES POSSESSED by molecules. (iii) Energy which is affected while heating. (IV) Energy which is affected during change in phase.

Discussion

664.	In solids, the particles move about
Answer» other particles their FIXED POSITION independently do not move Solution :their fixed position

Discussion

665.	In Sn+HNO_3toSn(NO_3)_2+H_2O+NH_4NO_3, the valencies of Sn are _________ .
Answer» ANSWER :0 and 2

Discussion

666.	In rat poison, phosphorous is used in the form of "___________"
Answer» SOLUTION :ZINC PHOSPHIDE

Discussion

667.	In methane, all the hydrogens can be replaced by chlorine atoms when the reaction takes place in presence of sunlight.
Answer» ANSWER :TRUE

Discussion

668.	In J.J Thomson's experiment , what obervations were found when (a) a small obstruction was placed in the path of cathode rays. (b) a paddle wheel is placed between cathode and anode. What were the conclusions drawn on the basis of these observations ?
Answer» SOLUTION :(i) Casting of SHADOW , path followed by cathode RAYS. (II) Rotation of wheel, have mass and KE.

Discussion

669.	In free state, carbon occurs as.....................and......................
Answer» ANSWER :DIAMOND; graphite/coal

Discussion

670.	In exothermic reactions, the energy of products is more than the energy of reactants.
Answer» ANSWER :FALSE

Discussion

671.	In elcctrothcrmic reduction, calcium phosphate is mixed with
Answer» SAND, sulphur coke, sand sulphur, coke sulphur, phosphorus SOLUTION :In electrothermic reduction calcium PHOSPHATE is mixed With sand and coke

Discussion

672.	In Castner-Kellner cell, sodium ions react with mercury to form "___________"
Answer» SOLUTION :SODIUM AMALGAM

Discussion

673.	In binary compounds, suffix __________ is added to the second element.
Answer» ANSWER :IDE

Discussion

674.	In an industry, H_2S gas is mixed with chlorine gas before releasing it into the atmosphere. Give the appropriate reason.
Answer» SOLUTION : `H_2S` gas is POISONOUS and the antidote for this gas is chlorine. Chlorine has the property to Components of soap destroy the effect of `H_2S` by OXIDIZING it to SULPHUR

Discussion

675.	In an endothermic reaction energy absorbed is more than the energy released.
Answer» ANSWER :T

Discussion

676.	In an atom , the number of neutrons is 58.7% more than that of protons. The number of electrons in the neutral atom is 92. Find out the number of protons , neutrons and mass number and represent the atom with atomic number and mass number.
Answer» Solution :Since the number of ELECTRONS in the neutral ATOM is 92. `THEREFORE ` Atomic number (Z)is 92 and number of PROTONS is 92 Number of neutrons `=92+(58.7xx92)/(100)=146` Mass number (A) =atomic number + number of neutrons Mass number =92 + 146 =238 Representation `""_(92)X^(238)`

Discussion

677.	In alpha-ray scattering experiment what would happen if(a) protons are used instead of alpha-particles.
Answer» Solution :If protons are used INSTEAD pf `alpha`-particles , the angles of deflection would be different because the charge of a proton is HALF of the charge of an `alpha`-particle and mass is almost`1//4^(th)` of the mass of an `alpha`-particles . Angle of deflection depends on both, the charge as WELL as the mass.

Discussion

678.	In alloys consituent metals retain their ______ properties .
Answer» SOLUTION :CHEMICAL

Discussion

679.	In a chemistry lab, a laboratory assistant by mistake placed one currency note with denomination of 100 on the desk and some amount of alcohol fell on it. The currency not was completely wet with alcohol. In order to dry it he immediately brought a burning match stick and exposed the currency note to its flame. Immediately the currency caught fire. But after few seconds, firs was put off by him and the note remained intact. Explain.
Answer» Solution :Currency notes are made up of THICK papers and the ignition tepmperature of this TYPE of paper is higher than the ordinary paper. When currency notes is soaked in alcohol, which has LOW ignition TEMPERATURE and high volatility it vapourises and burns before the ignition temperature of the paper is reached. Hence, the currency note does not burn.

Discussion

680.	Impure granulated zinc is preferred to pure zinc for the preparation of hydrogen . How do you account for this ?
Answer» Solution :(i) The mode of reaction between zinc and ACID (ii) Role of Zn. (iii) Change in property of Zn in GRANULATED form and PURE form. (IV) Comparison of the reactivity of hydrogen in PRESENCE of granulated zinc and pure zinc.

Discussion

681.	Immiscible liquids can be separated by
Answer» FRACTIONAL distillation separating funnel filtration decantation Answer :B

Discussion

682.	Imagine that it is a rainy day. What kind of umbrella would you use and why?
Answer» Answer :On a RAINY day, we use umbrella made of synthetic fibres because of the following ADVANTAGES:(i) It DRIES up quickly.(ii) It is DURABLE.

Discussion

683.	If ""_(x)^(y)A^(+1) " or " ""_(x-1)^(y-2)B^(+1) were to be used instead of alpha particles in Rutherford's experiment , which would be better and why ?
Answer» Solution :The results of RUTHERFORD's `alpha`-ray scattering EXPERIMENT are very clear if the deflections are large. As LIGHTER particle show larger deflections, `B^(+1)` would be preferable.

Discussion

684.	If the molecular weight of a compound Na_xSO_y is 142, then the values of X and Y are respectively __________ and __________ .
Answer» ANSWER :2,4

Discussion

685.	If the maximum permissible orbits of elements in nature are limited to n=4 , what are the number of possible elements ?
Answer» Solution :(i) Calculation of the maximum NUMBER fo ELECTRONS in each ORBIT. (ii) The number of elements that depend on electronic configuration . (III) The maximum number of electrons in the valence SHELL.

Discussion

686.	If the average atomic mass fo chlorine is 35.5 then find the percentage abundance of the two isotopes of chlorine which have the mass number 35 and 37.
Answer» Solution :(i) If the PERCENTAGE ABUNDANCE of Cl-35 is x , then `(x xx35+(100-x)37)/(100)=35.5` (ii) `75%` of Cl-35 and 25% of Cl-37.

Discussion

687.	If mass of apparatus is kept constant, mass of reactants is not equal to products.
Answer» ANSWER :F

Discussion

688.	If Glauber salt, anhydrous calcium chloride, calcium oxide and concentrated H_(2)SO_(4)are kept in air light container A,B, C,D respectively , in which container pressure becomes more ?
Answer» A B C D Answer :A::C

Discussion

689.	If an oxide does not form salt whenit reacts with acids or bases, it is called
Answer» basic acidic amphoteric neutral Answer :D

Discussion

690.	If an electron jumps from orbit A to orbit B it loses energy while it jumps from C to B it gains energy. Arrange the orbits in the increasing order of distance from the nucleus.
Answer» ` A LT B lt C` `C lt A lt B` `C lt B lt A` `A lt C lt B` Solution : When an electron jumps from a higher orbit to a lower orbit it loses energy and vice versa C is K shell NEAR to nucleus B is L shell followed by C A is M shell followed by B `THEREFORE` Increasing order fo distance from the nucleus is `C lt B lt A`

Discussion

691.	if a solution is formed by combination of solvent A and solid solute B, and decomposition of the solute takes place at boiling point of solvent, how can we separate these two?
Answer» SOLUTION :At the temperature at which SOLVENT 'A' boils, the solute 'B' decomposes. Hence it is not possible to separate the solute 'B' from solvent 'A' by distillation under normal atmospheric pressure. As the pressure decreases the boiling point decreases. Thus by decreasing the external pressure in the above distillation processes, the boiling point of solvent 'A' can be decreased. At this temperature solute 'B' does not decompose and can be separated from the LIQUID.

Discussion

692.	If a balloon filled with air is sent to moon, what would happen?
Answer» The balloon expands because the atmospheric pressure of the MOON is slightly lower than that of earth. The balloon BURSTS because the atmospheric of the moon is much lower than that of earth. The balloon CONTRACTS because the atmospheric pressure of the moon is much lower than that of earth. No CHANGE is observed because change of atmospheric pressure has no EFFECT on the balloon. Answer :B

Discussion

693.	Identify the type of chemical change that silver chloride undergoes in photo grey lenses.
Answer» SOLUTION :SILVER chloride PRESENT in the photo gray LENSES undergoes photolysis and gives silver and chlorine. `2AgCloverset("Sunlight")to2Ag+Cl_2` It is a decomposition reaction as well as a redox reaction as silver LOSES an electronegative element that is chlorine. Silver undergoes reduction while chlorine undergoes oxidation.

Discussion

694.	Differentiate between : Reactants and products
Answer» Solution :Reactant are Mg (Magnesium) and `O_(2)` (Oxygen). PRODUCT is MGO (Magnesium OXIDE)

Discussion

695.	Identify the heterogeneous mixture among the following.
Answer» BRINE solution Duralumin Gun powder Liquor ammonia Answer :C

Discussion

696.	Identify the electronic configuration of manganese (Z=25)
Answer» 2,8,13,2 2,8,8,7 2,8,15 2,8,10,5 Solution :ELECTRONIC CONFIGURATION of MAGANESE is 2,8,13,2 .

Discussion

697.	Identify the binary solution among the following .
Answer» Steel Bronze Nichrome Gun metal Answer :C

Discussion

698.	Identify the atomic number corresponding to least number of valence electrons
Answer» 19 15 35 34 Solution :The electronic confriguration of element with atomic number 19 is 2, 8 , 8 , 1, number of VALENCE electrons are 1 similarly the electronic configuration of ELEMENTS with atomic number 15 , 35 , and 34 , are 2, 8 , 5 , 2 , 8 , 18 ,7 , 2 , 8 ,18 , 6 respectively and the valence electrons are 5 , 7 and 6 respectively .So the atomic number corresponding to least number of valence electrons is 19.

Discussion

699.	Identify endothermic reaction among the following.
Answer» PASSAGE of `CO_(2)` through red hot carbon. Passage of `O_(2)` through red hot carbon. Burning of methane. Burning of WATER GAS. ANSWER :A

Discussion

700.	I heard that magnesium is found in plants. In what form is it found in them ?
Answer» Answer :YES, magnesium is found in PLANTS. Magnesium is found in the CHLOROPHYLL of the plants.

Discussion

Explore topic-wise InterviewSolutions in .

Incomplete burning of fuels produces carbon monoxide.

In winter mornings , the exhaled air turns foggy. Explain.

In which way in water useful for generating electricity ?

In which of the following uses of nitrogen, its characteristic property of insert nature is not exploited?

In which of the following subtances, intermolecular force of attraction is the maximum?

In what forms does sulphur occur in the combined state in nature?

In Thomson's atomic model, positive mass occupies more space than the negative charge in an atom.

In the welding of railway tracks, a proper proportion of aluminium powder and iron (iii) oxide are made to react with each other at high temperature. Explain the type of reaction involved and also identify the reducing and the oxidizing agents.

In the welding of railvvay tracks, a proper proportion of aluminium powder and iron (III) oxide arc made to react with each other at high temperature. Explain the type of reaction involved and also identify the reducing and the oxidizing agents.

In the manufacture of silicon carbide by Acheson process, sawdust is used along with sand and coke in the electric furnance. What is the main purpose of using sawdust as one of the constituents of the mixture ?

In the manufacture of graphite by Acheson process, the chargefilled between the cathode and anode consist of

In the laboratory preparation of carbon dioxide, carbon dioxide is collected by:

In spite of supplying heat, the temperature of the melting solid does not change. Explain with reasons.

In solids, the particles move about

In Sn+HNO_3toSn(NO_3)_2+H_2O+NH_4NO_3, the valencies of Sn are _________ .

In rat poison, phosphorous is used in the form of "___________"

In methane, all the hydrogens can be replaced by chlorine atoms when the reaction takes place in presence of sunlight.

In J.J Thomson's experiment , what obervations were found when (a) a small obstruction was placed in the path of cathode rays. (b) a paddle wheel is placed between cathode and anode. What were the conclusions drawn on the basis of these observations ?

In free state, carbon occurs as.....................and......................

In exothermic reactions, the energy of products is more than the energy of reactants.

In elcctrothcrmic reduction, calcium phosphate is mixed with

In Castner-Kellner cell, sodium ions react with mercury to form "___________"

In binary compounds, suffix __________ is added to the second element.

In an industry, H_2S gas is mixed with chlorine gas before releasing it into the atmosphere. Give the appropriate reason.

In an endothermic reaction energy absorbed is more than the energy released.

In an atom , the number of neutrons is 58.7% more than that of protons. The number of electrons in the neutral atom is 92. Find out the number of protons , neutrons and mass number and represent the atom with atomic number and mass number.

In alpha-ray scattering experiment what would happen if(a) protons are used instead of alpha-particles.

In alloys consituent metals retain their ______ properties .

Impure granulated zinc is preferred to pure zinc for the preparation of hydrogen . How do you account for this ?

Immiscible liquids can be separated by

Imagine that it is a rainy day. What kind of umbrella would you use and why?

If ""_(x)^(y)A^(+1) " or " ""_(x-1)^(y-2)B^(+1) were to be used instead of alpha particles in Rutherford's experiment , which would be better and why ?

If the molecular weight of a compound Na_xSO_y is 142, then the values of X and Y are respectively __________ and __________ .

If the maximum permissible orbits of elements in nature are limited to n=4 , what are the number of possible elements ?

If the average atomic mass fo chlorine is 35.5 then find the percentage abundance of the two isotopes of chlorine which have the mass number 35 and 37.

If mass of apparatus is kept constant, mass of reactants is not equal to products.

If Glauber salt, anhydrous calcium chloride, calcium oxide and concentrated H_(2)SO_(4)are kept in air light container A,B, C,D respectively , in which container pressure becomes more ?

If an oxide does not form salt whenit reacts with acids or bases, it is called

If an electron jumps from orbit A to orbit B it loses energy while it jumps from C to B it gains energy. Arrange the orbits in the increasing order of distance from the nucleus.

if a solution is formed by combination of solvent A and solid solute B, and decomposition of the solute takes place at boiling point of solvent, how can we separate these two?

If a balloon filled with air is sent to moon, what would happen?

Identify the type of chemical change that silver chloride undergoes in photo grey lenses.

Differentiate between : Reactants and products

Identify the heterogeneous mixture among the following.

Identify the electronic configuration of manganese (Z=25)

Identify the binary solution among the following .

Identify the atomic number corresponding to least number of valence electrons

Identify endothermic reaction among the following.

I heard that magnesium is found in plants. In what form is it found in them ?

If the molecular weight of a compound Na_xSO_y is 142, then the values of X and Y are respectively and .