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Chemistry (Engineering Entrance)

Description: Chemistry Mix Test - 3
Number of Questions: 20
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Tags: Chemistry Mix Test - 3 Chemical Bonding and Molecular Structure Polarity of Bond, Electronegativity Polarity of Bonds
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For the process K+(g) -----> K(g) - equation 1. K(g) ----->K (s) - equation 2 . Which statement is correct?

  1. Energy is absorbed in 1 and released in 2 .

  2. Energy is relesed in both the processes .

  3. Energy is released in 1 and absorbed in 2 .

  4. Energy is absorbed in both the cases .


Correct Option: B
Explanation:

In the first equation electron is added to a gaseous anion and energy is released in this process and in the second case also energy is released .

Which of the following statements is true ?

  1. Au > Cu > Ag ( ionization energy )

  2. I.Pcu > IPk ( IP- ionization potential ) . Cu -copper . K- potassium

  3. Hf > Zr > Ti ( atomic radius ) .

  4. Both option 1 and 2 are correct .


Correct Option: D
Explanation:

Both 1 and 2 are correct because , the electronic configuration of Au is given by  = Au = 4d10 4f14 6s1.  The electronic configuration of Ag is given by = Ag = 4d105s1 . The electronic configuration of Cu is given by = Cu = 3d10 4s1   . The effective nuclear charge of Au increases  because of  poor shieiding effect  of 4f14  electrons (  lanthanoid contraction ) , due to which its ionization energy is higher in its group .  electronic configuration of Cu is given by  - 3d104s1 .  electronic configuration of K is given by - 4s13d0 . In Cu poor shielding effect of  3d10 electrons causes increase in effective nuclear charge and because of this IP value of Cu is greater than that of K . Hence, both the options are correct.

Which of the following is least soluble in water?

  1. BaCrO4

  2. MgCrO4

  3. SrCrO4 .

  4. CaCrO4


Correct Option: A
Explanation:

 If abigger anion is attached to the alkali and alkaline earth metal groups , solubility decrease down the group . because solubilty depends on the the lattice energy  and hydration energy and in this case lattice energy > hydration energy . U lattice energy  = ( Z+ Z-) / (r + + r-) and  U hydration energy  = (Z+/r+) +( Z-/r- ) . Lattice energy increases down the group at faster rate than that of hydration energy . Hence, this option is correct.

Which of the following relations is correct regarding the increasing order of polarisibility?

  1. NaI < NaBr < NaCl .

  2. Mg3N2-3 > MgO-2 > MgF2-1 .

  3. MgF2-1< MgO-2 < Mg3N2-3 .

  4. NaCl < NaBr > NaI.


Correct Option: C
Explanation:

Polarisibilty is given by = (anionic charge) ( anionic charge) . charge of N , O , F  is same i.e -1 but the radius is in the order of  N > O > F. Hence, this option is correct . 

Which of the following relations is true regarding the higher melting point?

  1. CuCl < KCl

  2. SnCl2 < SnCl4

  3. CuCl > KCl .

  4. NaI > KCl .


Correct Option: A
Explanation:

The electronic configuration of Cu is given by  - 3d10 4s1 , therefore Cu+ has 3d10 4s0 . The electronic configuration of K is given by  - 4s1 3d0 . and therefore K+ has  4s0 3d0 . In Cu pseudo noble gas configuration is there because of this ionic potential of of Cu increases. It has more covalent character . Hence, less melting point . 

Which of the following is most stable?

  1. Pb+2

  2. Sn+2 .

  3. Si+2

  4. Ge+2


Correct Option: A
Explanation:

This option is correct. In Pb+2 inert pair effect is there i.e. because of lanthanoid contraction , poor shieding effect of  4f14  electrons . The effective nuclear charge increases and after removal of two  electrons it becomes really hard to remove the other two electrons . Hence, Pb+2 is most stable among its group because lanthanoids contraction observe in this atom only .

The correct order of conductivity is

  1. BeSO4 > MgSO4 > BaSO4 > CaSO4 .

  2. BaSO4 > CaSO4 > MgSO4 > BeSO4 .

  3. BaSO4 > MgSO4 > CaSO4 > BeSO4 .

  4. BeSO4 > MgSO4 > CaSO4 > BaSO4 .


Correct Option: B
Explanation:

The conductivity depends on the value of ionic potential . Higher the value of ionic potential lower is the conductivity. Ionic potential = charge of cation / radius of cation . µBe>µMg>µCa>µBa . Hence, this option is correct .

Bond order of CO+ is ?

  1. 3 .

  2. 3.5 .

  3. 2.5 .

  4. 7.5 .


Correct Option: B
Explanation:

this option is correct because , through  molecular orbital theory , we get the bond order of CO to be 3 . and the last electron lies  in the bonding molecual orbital but actually energy of sigma  antibonding 2sorbital is greater than that of sigma 2p orbital . hence the removal of electron takes place from  sigma  antibonding 2sorbital .  which increase the bond order to 3.5  which is calculated by the formula  1/2 (Nb- Na) , where Nb and Na are the number of electrons in bonding and anti - bonding orbitals respectively . 

Which of the following is correct order of lewis acidity ?

  1. SiI4 > SiBr4 > SiCl4 > SiF4 .

  2. BF3 > BCl3 > BBr3 > BI3 .

  3. SiF4 > SiCl4 > SiBr4 > SiI4 .

  4. BF3 > BCl3 < BBr3 < BI3 .


Correct Option: C
Explanation:

F2 > Cl2 > Br2 > I . hence the order of acidity is  SiF4 > SiCl4 > SiBr4 > SiI4 .

Arrange the following in order of decreasing Ionic mobility in protic solvent.

  1. Li+ > Na+ > K+ > Rb+ .

  2. Li+ > Na+ < K+ > Rb+ .

  3. Rb+ > K+ > Na+ > Li+ .

  4. Rb+ > K+ < Na+ > Li+ .


Correct Option: C
Explanation:

In protic solvent higher the value of ionic potential , highly hydrate  the cation is and therefore lower will be the mobilty . The ionic potential order is given by - Li+ > Na+ > K+ > Rb+ , therefore order of mobility is  - Rb+ > K+ > Na+ > Li+ .

Which of the following is more basic?

  1. ClO4H .

  2. ClOH

  3. ClO2H

  4. ClO3H


Correct Option: B
Explanation:

This option is correct because , in ClOH chlorine has three lone pair and the electron on O- is unable to delocalise itself . Hence, it will remain on oxygen atom and  has the highest basicity among the given options .  

Which of the following compounds is not hydrolysable?

  1. PF3 .

  2. NCl3 .

  3. PCl3 .

  4. NF3 .


Correct Option: D
Explanation:

This option is correct because , during the hydrolysis ,  water being neucleophile always prefer to attack the central atom first . it will attack the central atom  only when it posses vacant orbitals . If the central atom doesn't posses vacant orbital then attack  of water molecules taken place on peripheral atom provided they also posses vacant orbitals . in this case niether central nor peripheral atom posses vacant orbital hence hydroysis doesn't takes place in this molecule . 

Arrange the following in increasing order of basicity.

  1. NH3 < PH3 < AsH3 < BiH3

  2. NH3 < PH3 > AsH3 < BiH3

  3. BiH3 < SbH3 < AsH3 < PH3 < NH3

  4. BiH3 < SbH3 < AsH3 > PH3 < NH3


Correct Option: C
Explanation:

The electronic configuration of N is 1s2 2s2 2p3 . 's' and 'p' orbital of nitrogen atom requires energy in order to for the hybrid orbital . and after that it will combine with three hydrogen atoms in which energy is released which is greater than  the energy requires for the formation of hybrid orbital . If this condition is satisfies than only bond is formed . but in case of  phosphorus and higher elements these compensation of energy is not that much which compensate the energy of hybridization . hence each P orbital overlap individually & hence there bond angle  is around 90 degree and whatever fluctuation about 90 degree is because of replusion . As we move down the  group electron will be then donated form pure 's' orbital . Hence,  the correct order is BiH3 <  SbH3 < AsH3 < PH3 < NH3 .

Which of the following order of bond energy is correct ?

  1. N2 > N2+ = N2- .

  2. N2 < N2+ = N2- .

  3. N2 > N2+ > N2- .

  4. N2 > N2+ < N2- .


Correct Option: C
Explanation:

This option is correct. Bond order of N2 = 3. Bond order of N2+ = 2.5. Bond order of N2- = 2.5. Since bond order of N2+ and N2- is the same, but the effective nuclear charge of N2+ is more than that of N2-, so the correct order is N2 > N2+ > N2-.

The increasing order of dipole moment is

  1. CH3I < CH3Br < CH3Cl < CH3F

  2. CH3I > CH3Br > CH3Cl > CH3F

  3. CH3I < CH3Br < CH3F < CH3Cl

  4. CH3I < CH3Br > CH3F < CH3Cl


Correct Option: C
Explanation:

This option is correct because in the case of CH3F, magnitude of charge is the highest, but in the case of CH3Cl, the charge is almost the same as that of CH3F, but the separation between the charges overpowers. Hence, the magnitude of dipole moment of CH3Cl is greater than that of CH3F. Hence, the correct order is CH3I < CH3Br < CH3F < CH3Cl. 

Hybridization of XeF6 ?

  1. sp3d3 .

  2. Sp3d .

  3. sp3d3

  4. sp 3


Correct Option: C
Explanation:

You might have remembered  this logic  , if the total number of electrons comes out to be 50  the hybridisation is capped octahedral i.e. sp3d2 or distorted octahedral .  

Arrange the following in the decreasing order of bond angle.

  1. Fl2O > H2O > Cl2O

  2. Fl2O = H2O > Cl2O

  3. Cl2O > H2O < Fl2O .

  4. Cl2O > H2O > Fl2O


Correct Option: D
Explanation:

this option is correct. In Cl2O ,  the two lone pair of electrons on Oxygen atom get associated in making of  Pπ - d π back bonding with the empty 'd' orbital of Cl  and this replusion is higher as compared to other options . In the case of H2O ,  oxygen is more electronegative than hydrogen. Hence,  the  shared pair of electrons will lie more closer to oxygen than hydrogen and  the bond pair - bond pair replusion is there which is more than the replusion between the electrons density of two florine atoms in case of Fl2O . 

Which of the following statement is incorrect ?

  1. N-F bond length in NF3 is shorter than B-F bond length in BF3 .

  2. B-F bond length in BF3 is shorter than than B-F bond length in BF3 -NH3 .

  3. PH3 is weaker base than that of NH3 .

  4. In S2O3-2 both the sulphur atom has different oxidation state .


Correct Option: A
Explanation:

 this option is correct because , in BF3 boron has empty 'p' orbital in which non bonded electrons of Fluorine accommodate and form pπ - pπ back bond . due to which bond length decreases . hence  this statement  is incorrect . and  this  option is correct  . 

Paramagnetism is exibited by ?

  1. ClO2 .

  2. N2O .

  3. Cl2O .

  4. ClO3 ( solid state dimerize ) .


Correct Option: A
Explanation:

this option is correct because , in case of homoneuclear molecule it is easy to calculate the magnetic character through molecular orbital theory . but in case of hetronuclear molecule one  easy method is there to find out the magnetic character . magnetic character in case of hetronuclear molecules . 1. count  the total number of valence electrons if it comes out to be even then it is dimagnetic otherwise paramagnetic . in this case Cl has 7 valence electrons and oxygen has 6 valence electrons . so total number of valence electrons is 7 + 6 x 2 = 19 , which is odd hence this molecule is paramagnetic . and this option is correct  .   

Arrange the following in decreasing order of bond energy.

  1. F2 > Cl2 > Br2 > I2

  2. Cl2 > Br2 > F2 > I2

  3. F2 > Cl2 < Br2 > I2

  4. I2 > Br2 > Cl2 > F2


Correct Option: B
Explanation:

pπ- pπ back bonding is there  in Cl due to which partial double bond character is there and hence, it is higher in order , but in case of bromine partial double bond, character is there but because of its large size double bond character is less than that in the case of Cl2 . This double bond character is not observe in case of iodine because of its large size . Florine has smaller in size than  iodine therefore it is above the iodine in order . Hence, the correct order  is Cl2 >  Br2 > F2 > I2

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