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87401.

A solid is made of two elements X and Z. The atoms Z are in C.C.P. arrangement while atoms X occupy all the tetrahedral sites. What is the formula of the compound-

Answer»

XZ
` XZ_(2)`
`X_(2)Z`
Unpredictable

Answer :C
87402.

A solid is formed by two elements P and Q. The element Q forms cubic close packing and atoms of P occupy two-third of tetrahedral voids. The formula of the compound is

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`PQ_(3)`
`P_(3) Q`
`P_(2)Q_(3)`
`P_(3)Q_(2)`

Solution :Let the no. of Q atoms = n
No. of tetrahedral VOIDS = 2N
No. of P atoms `=2n XX ( 1)/( 3)= ( 2n )/( 3)`
FORMULA `: P : Q `
`( 2n )/( 3) : n ` or `2:3 ` `:. P _(2) Q_(3)`
87403.

A solid is formed and it has three types of atoms X, Y, Z. X forms an FCC lattice with Y atoms occupying one-fourth of tetrahedral voids and Z atoms occupying half of the octahedral voids. The formula of the solid is

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`X_4 Y_4 Z_2`
`X_2 Y Z_2`
`X_4 Y Z`
`X_2 Y Z`

ANSWER :D
87404.

A solid having no definite geometrical shape with flat faces and sharp edges is :

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AMORPHOUS solid
Crystalline solid
Isotropic solid
None

Answer :B
87405.

A solid has a structure in which "W" atoms are located at the corner of the cubic lattice "O" atoms at the centre of edge and Na atom at the centre of cube. The formula of the compound is ...........

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`NaWO_2`
`Na_2WO_2`
`NaWO_3`
`Na_2WO_3`

Solution :Number of W atoms = `( 8 xx 1/8) = 1`
Number of Na atoms = 1
Number of O atoms `= (12 xx 1/4) = 3`
`THEREFORE Na : W : O = 1 : 1 : 3 implies NaWO_3`.
87406.

A solid has a strcture in which 'W' atoms are located at the corners of a cubic lattice 'O' atoms at the centre of edges and 'Na' atoms at the centre of the cube. The formula for the compound is

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`NaWO_(2)`
`NaWO_(3)`
`Na_(2)WO_(3)`
`NaWO_(4)`

SOLUTION :In a unit cell, W atoms at the corner `=(1)/(8)xx8=1`
O atoms at the centre of edges `=(1)/(4)xx12=3`
Na atoms at the centre of the cube=1
`W:O:Na=1:3:1`, hence formula =`NaWO_(3)`
87407.

A solid having density of 9 xx 10^3 "kg m"^(-3) form face centred cubic crystals of edge length 200sqrt(2) pm. What is the molar mass of solid ? (Avogadro's constant = 6 xx 10^23 "mol"^(-1), pi = 3)

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`0.0216 "kg MOL"^(-1)` 
`0.0432 "kg mol"^(-1)`
`0.4320 "kg mol"^(-1)` 
`0.0305 "kg mol"^(-1)`

Solution :`d = (Z xx M)/(a^3 xx N_A)`
`THEREFORE 9 xx 10^3 = (4 xx M)/((200 sqrt(2))^3 xx 10^(-36) xx 6 xx 10^(23))`
`therefore M = 0.0305 "kg mol"^(-1)`.
87408.

A solid has a structure in which W atoms are located at the corners of the cubic lattice, O atoms at the centre of the edges and Na atom at the centre of the cube. The formula of the compound is

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`NawO_(2)`
`Na_(2)WO_(3)`
`NaW_(O_(3))`
`NaWO_(4)`

ANSWER :C
87409.

A solid has a bcc structure. If the distance of closest approach between the two atoms is 1.73overset@A.The edge length of the cell is :

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200 pm142.2 pm

Answer :A
87410.

A solid has a b.c.c. structure . If the distance of closest approach between the two atoms is 1.73 Å. The edge length of the cell is :

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199 PM
`SQRT(3//2)` pm
142.2 pm
`SQRT2` pm

ANSWER :A
87411.

A solid element burns in oxygen without any change in volume (of gas) under similar conditions of temperature and pressure. If the vapour density of pure gaseous product is 32, what is the equivalent mass of the element?

Answer»

SOLUTION :One vol. of oxide contains 1 VOLT. Of `O_(2)`.
One MOLE of oxide contains one mole of `O_(2)`.
Mol. Mass of oxide `=A=32=2V.D.=64`
32 PARTS of element combine with 32 parts of oxygen.
So, equivalent mass of element`=(32)/(32)xx8=8`
87412.

A solid dissolves in water exothermically, if its saturated solution at 20^@C is cooled to 0^@C then:-

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Some solid separates out
Some ICE separates out
Both the solid and ice separate
NEITHER the solid nor the ice separates out

Solution :Due to DEPRESSION in P.P, WATER will freeze at a temperature LESS than `0^@C`.
87413.

A solid crystal is composed of X, Y and Z atoms. Y atoms are occupying 50% of octahedral voids, whereas X atoms are occupying the 100 % tetrahedral void with Z atoms in ccp array arrangement, then the number of Y atoms in rational formula the given cell.

Answer»


ANSWER :4
87414.

A solid cube of edge length =25.32 mm of an ionic compound which has NaCl type lattice is added to 1kg of water.The boiling point of this solution is found to be 100.52^@C(assume 100% ionisation of ionic compound).If radius of anion of ionic solid is 200 pm then calculate radius of cation of solid in pm (picometer). (K_b of water =0.52 K kg "mole"^(-1),Avogadro's number,N_A=6xx10^(23),(root3(75))=4.22)

Answer»


Solution :Effective molality of solution=1
Hence, number of moles of IONIC solid in GIVEN cube=0.5
So, number of formula units in given cube `=0.5xx6xx10^(23)`
Number of units cells `=1/4xx0.5xx6xx10^23=7.5xx10^22`
number of unit cells along ONE edge of cube `=root(3)(75)xx10^7=4.22xx10^7`
edge length of unit cell =`a=(25.32xx10^(-3))/(4.22xx10^7)m=600xx10^(-12) m =600` pm
forNaCl type unit cell, `a=2(r_(+)+r_(-)) " " IMPLIES " " r_(+)=100` pm
87415.

A solid compound XY has NaCl structure . If the radius of the cation is 100 pm , the radius of the anion will be ……..

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`((100)/(0.414))`
`((0.732)/(100))`
`100 xx 0.414`
`((0.414)/(100))`

Solution :`((100)/(0.414))`
For an FCC structure `(r_(X))/(r_(Y)) = 0.414` , gives that `r_(X) = 100` PM `r_(Y) = (100 "pm")/(0.414)`
87416.

A solid compound XY has NaCl structure. If the radius of the cation is 100 pm, the radius of the anion will be………………

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`((100)/(0.414))`
`((0.732)/(100))`
`100xx0.414`
`((0.414)/(100))`

Solution :HINT : For an FCC STRUCTURE `(r_(X^(+)))/(r_(y^(-)))=0.414`
GIVEN that `r_(X^(+))="100 PM "r_(y^(-))=("100 pm")/(0.414)`
87417.

A solid compound 'X' on heating gives CO_(2) gas and a residue. The residue mixed with water forms 'Y'. On passing an excess of CO_(2) through Y in water, a clear solution 'Z' is obtained. On boiling 'Z' compound 'X' is formed. The compound 'X' is

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`CaCO_(3)`
`Na_(2)CO_(3)`
`K_(2)CO_(3)`
`Ca(HCO_(3))_(2)`

ANSWER :A
87418.

A solid compound contains X,Y and Z atoms in a cubic lattice with X atoms occupying the corners. Y atoms in the body centered positions and Z atoms at the centres of faces of the unit cell. What is the empirical formula of the compound.

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`XY_(2)Z_(1)`
`XYZ_(3)`
`X_(2)Y_(2)Z_(3)`
`X_(8)YZ_(6)`

Solution :Atoms of X PER UNIT cell `=8xx(1)/(8)=1`
Atoms of Y per unit cell `=1`
Atoms of Z per unit cell `=6xx(1)/(2)=3`
Hence the formula is `XYZ_(3)`.
87419.

Asolid compound contains XYZ atoms in a cubic lattice with X atoms occupying the corners, Y atomsin the body centred positions and Z atoms at the centres of faces of the unit cell. What is the empirical formula of the compound

Answer»


ANSWER :`XYZ_3`
87420.

A solid catalyst is more effective in its finely divided form - Justify.

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SOLUTION :Finely divided FORM of a catalyst has GREATER surface area when compared to their crystalline form. Greater the surface area, greater the ADSORPTION and HIGHER the catalytical activity.
87421.

A solid AB has ZnS-type structure. The edge lenth of unit cell is 400 pm abd the radius of B^- ion is 0.130 nm. Then the radius of A^+ ion is

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35.8 pm
43.2 pm
60.5 pm
53.2 pm

Answer :B
87422.

A solid AB has the NaCl structure. If the radius of the cation A^(+) is 150 pm, calculate the maximum possible value of the radius of the anion B^(-).

Answer»


Solution :For the NACL type structure, `(R^(+))/(r^(-))= 0.414 -0.732`
`:. r^(+) = 150` PM and for MAXIMUM value of `r^(-), (r^(+))/(r^(-)) = 0.414`
`:. (150)/(r^(-))= 0.414` or `r^(-) =(150)/(0.414) = 362.3` pm
87423.

A solid AB has rock salt structure. If the radius of cation is 100 pm, the maximum radius of anion B^(ө)is ...........

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120.7 PM
68.3 pm. 
136.61 pm. 
241.54 pm 

SOLUTION :`(R^+)/(r^-) = 0.414 IMPLIES r^(-) = (100)/(0.414) = 241.54`
87424.

A solid AB has NaCl structure. If the radius of cation A^(+) is 160 pm, calculate the maximum possible value of radius of the anion B^(-)?

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Solution :The RADIUS ratio of `A^(+)` and `B^(-)` having `Na^(+)Cl^(-)` structure is = 0.414 to 0.732
`:. ("Radius of cation, "A^(+))/("Radius of anion, "B^(-))` = 0.414 to 0.732
`:. "Radius of anion "B^(-)=("Radius of cation, "A^(+))/("0.414 to 0.732") = (160)/("0.414 to 0.732")` = 386.47 to 218.58 PM
`:.` Maximum POSSIBLE value of the radius of the anion `B^(-) = 386.47` pm
87425.

A solid (A) which has photographic effect reacts with the solution of a sodium salt (B) to give a pale yellow ppt. (C). Sodium salt on heating gives brown vapour. Identify A, B and C

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`AgNO_(3),NaBr,AgBr`
`AgNO_(3),NACL,AgCl_(2)`
`AgNO_(3),NaBr,AgCl_(2)`
`AgCl,NaBr,AgBr_(2)`

ANSWER :A
87426.

Asolid A^+B^-has the B^-ions arranged as below .If the A^+ ions occupy half of the tetrahedral sites in the structure. The formula of solid is :

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AB
`AB_2`
`A_2B`
`A_3B_4`

ANSWER :C
87427.

A sol of egg albumin can be coagulated by addition of :

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ELECTROLYTES
Alcohols
Both electrolytes and alcohols
None of these

Answer :C
87428.

A sol may be prepared by a precipitation reaction. Give one such example. How can we find the nature of electric charge on the sol particles ?

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Solution :`As_2S_3` SOL MAY be prepared by precipitation reaction as per the following reaction :
`As_2O_3 + 3H_2S to As_2S_3 + 3H_2O`
We can FIND the nature of charge on colloidal solution by electrophoresis. The colloidal PARTICLES move towards the oppositely charged electrode in an electric field. For example, the colloidal solution of `As_2O_3` is negatively charged and moves towards positive electrode.
87429.

A soild, A which has photographic effect reacts with the solution of a sodium salt B to give a pale yellow precipitate C. Sodium salt on heatinggives brown vapours. Identity A,B and C.

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`AgNO_(3),NaBr,AgBr`
`AgNo_(3),NaCl,AgNO_(3)`
`AgNO_(3),NaBr,AgCl_(2)`
`AGCL,NaBr,AgBr_(2)`

Solution :A solid silver nitrate `[AgNO_(3)(A)]` which has photographic effect reacts with the solution of NaBr (B) to give a pale YELLOW ppt. of AgBr which experience difficulty to be SOLUBLE in `NH_(4)OH NaBr` (B) on heating brown vapours of bromine.
`underset(A)(AgNO_(3))+underset(B)(NaBr)rarrunderset(underset("Light yellow ppt.")(C))(AgBr+NaNO_(3))`
87430.

A sodium salt X of an unknown anion when treated with MgCl_(2) gives precipate Y only on boiling. It gives lime water test positive but doesn't gives KMnO_(4) test. Compound X and Y can't be seperated by using.

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Phenolphtalein TEST
`AgNO_(3)` test
`CaCl_(2) ` test
`Hg_(2)(NO_(3))_(2)` test

Answer :A
87431.

A sodium salt on treatment with MgCl_2 gives white precipitate only on heating. The anion of sodium salt is:

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`HCO_3^(-) `
`CO_3^(2-)`
`NO_3^(-) `
`SO_4^(2-)`

Solution :`MgCl_2 + NaHCO_3to UNDERSET("SOLUBLE")(Mg(HCO_3)_2)+2NaCl`
`Mg(HCO_3)_2 overset("HEAT")to MgCO_3 + H_2O + CO_2 UARR `
87432.

A sodium salt on treatment with MgCl_(2) gives white precipitate only on heating. The anion of sodium salt is

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`HCO_(3)^(-)`
`CO_(3)^(2-)`
`NO_(3)^(-)`
`SO_(4)^(2-)`

Solution :N//A
87433.

A sodium salt (A) when reacts with dilute HCI produces a salt and a colouless, rotten egg smelling gas (B). (B) when passed through lead acetate solution produces a black precipitate (C). Futher (C) on treatment with H_(2) O_(2) solution yields a white precipitate (D). Identify (A).

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`H_(2) S`
`Na_(2) S`
`Na_(2) SO_(4)`
`PbSO_(4)`

Solution :As the GAS has rotten egg smell, so it may be `H_2S`. Hence the salf is sodium sulphide . Thus , `A = Na_2S, B= H_2S, C = PbS, D = PbSO_4`
`underset((A))(Na_2S)+ 2HCL to 2NaCl + underset((B))(H_2S)`
`Pb(CH_3COO)_(2) + H_2S to underset(("BLACK PPT."))underset((C))(PbS darr) + 2CH_3COOH`
`PbS + 4H_2O_2 to underset(("WHITE ppt."))underset((D))(PbSO_4) darr + 4H_2O` .
87434.

A sodium salt of an unknown anionwhentreates with MgCI_(2)gives whiteprecipitate onlyon boling .The anion is

Answer»

`SO_(4)^(2-)`
`HCO_(3)^(Θ)`
`CO_(3)^(2-)`
`NO_(3)^(Θ)`

Solution :It must be a bicarbonate ionbecausefirst magnesiumbeicarbonate isformed which is soluble , then onheating , magnesiumcarbonate is formed which is a insoluble and FORMS a precipitate
`MgCI_(2) + 2NaHCO_(3) RARR underset("soluble")((Mg(HCO_(3))_(2)) + 2NaCI`
`Mg(HCO_(3))_(2) OVERSET(Delta)(to) underset(white)(MgCO_(3) darr) + H_(2)o + co_(2)`
87435.

(a) Sodium metal crystallizes in bcc structure. Its unit cell edge length is 420 pm. Calculate its density. (Atomic mass of sodium = 23 u, N_(A) = 6.022 xx 10^(23) mol^(-)). (b) What is Frenkel defect ? How does it affect the density of a crystal ?

Answer»

Solution :(a) Density `= (Z.M)/(a^(2) N_(A))`
`= (2 XX 23 xx 10^(-3))/(420 xx 10^(-12) xx 6.022 xx 10^(23))`
`= 1.031 xx 10^(3) kg//m^(3)`
(b) This is a defect caused by the DISLOCATION of a smaller ION from its normal site to an intersitial site.
Density does not change.
87436.

(A) Sodium can't be used for drying ethyl alcohol.(R) Sodium displaces hydrogen from ethyl alcohol.

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Both A & Rare true, R is the correct EXPLANATION of A
Both A & Rare true, R is not correct explanation of A
A is true, R is FALSE
A is false, R is true

Answer :A
87437.

A + SOCl_2 to B + SO_2 + HCl X + Na to C + H_2B + C to (C_2H_5)_2O+ NaClThen A and X are respectively

Answer»

` C_2H_5CI and C_2H_5ONa`
` C_2H_5ONa and C_2H_5Cl`
` C_2H_5OH and C_2H_5OH`
` C_2H_5OH and C_2H_5ONa`

ANSWER :C
87438.

A soap can be obtained by the saponificattion of

Answer»

Liquid paraffin
COCONUT OIL
LEMONGRASS oil
SANDAL wool

Answer :B
87439.

(A) SO_(2) gas is easily liquified while H_(2) isdifficult to liquify . (R ) SO_(2) has low critical temperature while H_(2) has high critical temperature.

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Both (A) and (R) are true and (R) is the correct explanation of (A) 
Both (A) and (R) are true and (R) is not the correct explanation of (A) 
(A) is true but (R) is FALSE 
(A) is false but (R) is true 

ANSWER :C
87440.

(A): SO_(3) molecule has a planar structure (R) : S atom in SO_(3) is sp^(2)- hybridized and O-S-O bond angle is 120^(@)

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Both (A) and (R ) are TRUE and (R ) is the CORRECT EXPLANATION of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is false
Both (A) and (R )are false

ANSWER :A
87441.

(A) SO _(2) acts as good reducing agent in aqueous solutions (R ) SO _(2) + 2 H _(O to H _(2) SO _(4) + 2 (H)

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Both (A) and (R ) are TRUE and (R ) is the CORRECT EXPLANATION of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is false
Both (A) and (R )are false

Answer :A
87442.

(A) SO _(2) is reducing agent and TeO _(2) is oxidising agent (R )From SO _(2) to TeO _(2) acidic nature of dioxides increases.

Answer»

Both (A) and (R ) are true and (R ) is the correct EXPLANATION of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is false
Both (A) and (R )are false

Answer :C
87443.

(A) SO _(2) is angular molecule (R ) In SO _(2) sulphur exhibit SP ^(2) hybridisation

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Both (A) and (R ) are true and (R ) is the correct explanation of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is FALSE
Both (A) and (R )are false

ANSWER :B
87444.

(A) SnCl_(4) is more covalent than SnCl_(2) (R ) Compound with higher oxidation state of metal is more covalent than with lower oxidation state

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Both (A) and (R ) are true and (R ) is the correct EXPLANATION of (A)
Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is FALSE
Both (A) and (R ) are false

Answer :A
87445.

(A) S_N2 reactions are exothermic (R) S_N2 reactions are thermochemically favored by stronger nucleophiles

Answer»

Both (A) and (R) are correct and (R) is the correct EXPLANATION of (A) 
Both (A) and (R) are correct but (R) is not the correct explanation of (A) 
(A) is TRUE but (R) is False 
Both (A) and (R) are false 

Answer :A
87446.

(A): S_(N^(2)) reaction takes place in single step.(R): S_(N^(2)) reaction involves the reactivity order of alkyl halides as 1^@ gt 2^@ gt 3^@ halides.

Answer»

Both A & R are TRUE, R is the correct explanation of A
Both A & R are true, R is not correct explanation of A
A is true, R is false
A is false, R is true

Answer :B
87447.

A smuggler could not carry gold by depositing iron on gold surface since

Answer»

gold has higher standard reduction potential than iron
gold has lower standard reduction potential than iron
gold is denser
iron rusts

Solution :A SMUGGLER could not carry gold by deposting iron on gold surfase. We KNOW that GREATER is the standard ELECTRODE potential of an electrode, the more is the TENDENCY of its ion to get induced. Since the standard reduction potential of `Au^(3+)//Au` is greater than `Fe^(2+)//Fe`, iron cannot be deposited on gold by electroplating.
87448.

A smuggler could not carry gold by depositing iron on the gold surface since

Answer»

Gold is denser
Iron rusts
Gold has higher REDUCTION POTENTIAL than iron
Gold has lower reduction potential than iron

Answer :C
87449.

A small sample of Uranium metal (0.119 gm) is heated to 900^(@) C in air to give 0.135 gm of a dark oxide, U_(x) O_(y). Then [U = 238]

Answer»

Moles of `U_(X) O_(y)` formed `= 5 xx 10^(-3)`
Empirical formula is `UO_(2)`
Moles of Uranium metal used `5 xx 10^(-4)`
Moles of oxygen gas used `1 xx 10^(-3)`

Solution :`{:(U,+,O_(2),rarr,U_(x)O_(y),):}`
Moles of `U = (0.119)/(238) = 0.5 xx 10^(-3) = 5 xx 10^(-4)`
Mass of oxygen in oxide `= (0.135 - 0.119)`
`= 0.016 gm`
Moles of oxgyen ATOM in oxide `= (0.016)/(16) = 1 xx 10^(-3)`
`{:(U,,O,),(5 xx 10^(-4),,1 xx 10^(-3),),(0.5,:,1,),(1,:,2,):}`
Emprical formula `= UO_(2)`
87450.

A small iodine crystal is added to each of the following aq solutions: I. sodium sulphate II. Sodiumthiosulphate III. Sodium tetrathionate IV. Sulphuric acid In which solutions the purple colour disappers

Answer»

only in I
only in I and II
only in III and IV
only in II

Answer :D