All questions of Chemical Bonding and Shapes of Compounds for Chemistry Exam

The hybridization state on BH3 is:
  • a)
    sp3d
  • b)
    sp
  • c)
    sp3
  • d)
    sp2
Correct answer is option 'D'. Can you explain this answer?

Vikram Kapoor answered
In BH3
We know that,
Boron has three valence electron, so it is supposed to make 3 bond in a molecules with hybridization sp2 as only S and two p are used in hybridization because last p orbital vacant.

Which one shows maximum hydrogen bonding?
  • a)
    H2Se
  • b)
    H2S
  • c)
    H2O
  • d)
    All have same
Correct answer is option 'C'. Can you explain this answer?

The correct option is : a H2O Explanation:H2O shows maximum H-bonding because each H2O molecule is linked to four H2O molecules through H-bonds.

The hybridization state in triangle bipyramidal CH5+ is:
  • a)
    sp
  • b)
    sp3d
  • c)
    sp3
  • d)
    sp2
Correct answer is option 'D'. Can you explain this answer?

Sahana Sharma answered
Carbonium ion methonium,  CH5+ is produced by the addition of  H+ to CH4. In CH5+ three hydrogen atoms are in a plane and one above and one below the plane. 
So its sp3d and the shape is trigonal bipyramid. 
But this compound is considered a CH3+ carbenium ion with a molecule of hydrogen interacting with the empty orbital in a 3-center-2-electron bond. As the two hydrogen atoms in H2 are in continuously exchange positions with the three hydrogen atoms in the CH3+ methonium  CH5+ is considered as a fluxional molecule. Due to the existence of CH3+ this is sp​2 hybridised. 

The percentage of p-character in the orbitals forming P−P bonds in P4 is
  • a)
    25
  • b)
    33
  • c)
    50
  • d)
    75
Correct answer is option 'D'. Can you explain this answer?

The percentage of p-character in forming P-P bonds in P4 molecule is: 0. In forming 
Pmolecule, P atom uses sp3 hybrid orbitals. Thus, the p-character in hybrid orbitals is 75%.

Examples of refractory materials include
  • a)
    MgO
  • b)
    LiCl
  • c)
    KF
  • d)
    CaCl2
Correct answer is option 'A'. Can you explain this answer?

Bijoy Kapoor answered
They are namely based on oxides and their compounds, the most important oxides are Al2O3, CaO, MgO, SiO2, Cr2O3, and ZrO2. The second type is non-oxide refractories. Example of non-oxide refractories are carbon-based refractory materials, and carbides, nitrides, borides, and silicides.

According to VSEPR theory, the molecule/ ion having ideal tetrahedral shape is:
  • a)
    SF4
  • b)
    SO42–
  • c)
    S2Cl2
  • d)
    SO2Cl2
Correct answer is option 'B'. Can you explain this answer?

Jay Nambiar answered
B)SO42- (sulfate ion) has ideal tetrahedral shape with four surrounding oxygen atoms arranged symmetrically around the central sulfur atom.

Arrange the following molecules in order of increasing bond polarit :
(I) H2O
(II) NH3
(III) PH3
(IV) H2S
  • a)
    I < II < III < IV
  • b)
    IV < III < II < I
  • c)
    III < IV < II < I
  • d)
    III < IV < I < II
Correct answer is option 'C'. Can you explain this answer?

Asf Institute answered
Correct Answer :- c
Explanation : The bond polarity is directly proportional to the electronegativity of the atom.
As we move down the group, radius of elements increases and electronegativity decreases so bond angle decreases.
So, bond polarity will be : H2O < NH3< H2S < PH3

The hybridization state in ‘B’ when BF3 form adduct with ether is:
  • a)
    sp
  • b)
    sp
  • c)
     sp2
  • d)
    sp4
Correct answer is option 'C'. Can you explain this answer?

For boron to bond with three fluoride atoms in boron trifluoride (BF3), the atomic s- and p-orbitals in boron's outer shell mix to form three equivalent sp2 hybrid orbitals.
 

The direction of dipole moment is correct in:
  • a)
  • b)
  • c)
  • d)
    All are correct.
Correct answer is option 'B'. Can you explain this answer?

Vedika Singh answered
In pyrolle there is greater resonance effect n due to more electronegativity in furan more inductive effect pronounced so the direction of dipole moment in furan is towards oxygen.

Hybridization in N2 is:
  • a)
    sp4
  • b)
    sp2
  • c)
    sp3
  • d)
    None
Correct answer is option 'D'. Can you explain this answer?

Sagarika Patel answered
The hybridization of O2 ,N2 and F2 is Sp2 , Sp, Sp3 . Steric factor = number of bonded atoms + number of lone pair . The hybridization of O2, N2, and F2are sp2, sp, sp3 respectively. As we know between O-O , there are two bonds one is sigma and other is pi bond.

Which has an exact angle of 120° among:
  • a)
    C2H4
  • b)
    BF3
  • c)
    HCHO
  • d)
    All
Correct answer is option 'B'. Can you explain this answer?

Chirag Verma answered
Boron trifluoride is planar and the bond angle is 120 degrees. This can be predicted from VSEPR theory. There are three bonding pairs of electrons and no lone pairs on the central atom

Hybridization and shape of N(SiH3)3 is:
  • a)
    Sp3, tetrahedral
  • b)
    sp2, planar
  • c)
    sp3, planar
  • d)
    sp2, angular
Correct answer is option 'B'. Can you explain this answer?

Hybridization and shape of N(SiH3)3:

Hybridization is the process of combining atomic orbitals to form hybrid orbitals that have different properties from the original atomic orbitals. The shape of a molecule is determined by the arrangement of its atoms and the hybridization of its orbitals.

The molecule N(SiH3)3 contains one nitrogen atom and three silicon atoms bonded to it. The nitrogen atom has one unpaired electron in its 2p orbital, which can be used to form three sigma bonds with the silicon atoms. The hybridization of the nitrogen atom is therefore determined by the number of sigma bonds it forms.

Option B is the correct answer because the hybridization of the nitrogen atom in N(SiH3)3 is sp2, and the shape of the molecule is planar.

Explanation:

1. Hybridization of the Nitrogen atom:

The nitrogen atom in N(SiH3)3 forms three sigma bonds with the silicon atoms, which requires three orbitals. Therefore, the nitrogen atom undergoes sp2 hybridization, in which one 2s orbital and two 2p orbitals combine to form three sp2 hybrid orbitals.

2. Shape of the Molecule:

The shape of the molecule is determined by the arrangement of its atoms and the hybridization of its orbitals. In N(SiH3)3, the three sp2 hybrid orbitals on the nitrogen atom are arranged in a trigonal planar geometry, with bond angles of 120 degrees. The three Si-H bonds are also arranged in a trigonal planar geometry around each silicon atom. Therefore, the shape of the molecule is planar.

Conclusion:

In summary, the correct answer for the hybridization and shape of N(SiH3)3 is sp2 and planar, respectively. The nitrogen atom undergoes sp2 hybridization to form three sp2 hybrid orbitals, which are arranged in a trigonal planar geometry around the nitrogen atom. The three silicon atoms are also arranged in a trigonal planar geometry around the nitrogen atom, resulting in a planar shape for the molecule.

Which of the following species has two non bonded electron pairs on the central atom:
  • a)
    TeCl4
  • b)
    ClF3
  • c)
    ICl2
  • d)
    PCl3
Correct answer is option 'D'. Can you explain this answer?

Garima Chavan answered
In TeCl4 out of 6 electrons:bonded electrons are 4,non-bonded electron pair is 1.
In ClF3 out of 7 electrons:bonded electrons are 3,non-bonded electron pairs are 2.
In PCl3 out of 5 electrons:bonded electrons are 3,non-bonded electron pair is 1.
In ICl2− out of (7+1=8) electrons:bonded electrons are 2,non-bonded electron pairs are 3.

With respect to hyper valence theory, which will have multicenter bonding:
  • a)
    B2H6
  • b)
    CH6++
  • c)
     SF4
  • d)
    All are correct
Correct answer is option 'A'. Can you explain this answer?

Yashvi Roy answered
Multicenter bonding is typically associated with compounds that exhibit bonding that cannot be explained by conventional two-center two-electron bonds. This often involves compounds with electron-deficient atoms or those that form hypervalent bonds.
Let's evaluate the options:
1. B2H6: Diborane (B2H6) is a classic example of a molecule with multicenter bonding. It has two bridging hydrogen atoms that are involved in three-center two-electron bonds, connecting two boron atoms. This is a well-known case of multicenter bonding.
2. CH6++: This is not a standard compound and seems hypothetical. Such a molecule would be highly unstable and could theoretically involve multicenter bonding, but it's not a commonly recognized species.
3. SF4: Sulfur tetrafluoride (SF4) is hypervalent and has 10 electrons around sulfur, but it does not involve multicenter bonding. The bonding in SF4 can be explained using standard two-center bonds.
 
Given that B2H6 clearly has multicenter bonding and the other options are either incorrect or ambiguous:
Correct Answer: 1. B2H6

Which will have zero dipole moment:
  • a)
    O2F2
  • b)
    H2O2
  • c)
    MnO4
  • d)
    All
Correct answer is option 'C'. Can you explain this answer?

Baishali Bajaj answered
Zero dipole moment is the dipole moment between two atoms being zero. It depends on the polarities of individual bonds and the geometry of the atoms.

For example CO2 , two opposing oxygen atom with carbon in the center as it’s geometry . The dipole bonds are equal in magnitude but opposite in nature. So, it has zero dipole moment.

But on the other hand water (H2O) has a oxygen atom at the top of a triangular structure while two hydrogen atoms take the place of the base sides. Here also the dipole bonds are equal in magnitude but not opposing each other. So, it has non-zero dipole moment.

The geometry of H2​S and its dipole moment are :
  • a)
    angular and non-zero
  • b)
    angular and zero
  • c)
    linear and non zero
  • d)
    linear and zero
Correct answer is option 'A'. Can you explain this answer?

Asf Institute answered
  • H2​S molecule has an angular geometry because it has two lone pairs of electrons that make the molecule bend. The dipole moment is not zero.
  • This is because sulfur is more electronegative than hydrogen, making the molecule slightly polar.

In which, lone pair is present in almost pure orbital:
  • a)
  • b)
  • c)
    SbH3
  • d)
    NH3
Correct answer is option 'C'. Can you explain this answer?

According to Drago's rule when the following conditions are satisfied, then the energy difference between the participating atomic orbitals will be very high and thus no mixing of orbitals or hybridization takes place.
  • At least one lone pair must be present on the central atom.
  • The central atom must be of 2nd period.
  • The electronegativity of the surrounding atom must be less than or equal to 2.1.
  • No hybridisation means bonding will take place through pure atomic p orbitals as in SbH3 and thus bond angle will be approximately equal to 900.

Which of the set of isomers of C6H4Cl2 is having equal dipole moment with C6H5Cl and C6H6 respectively
  • a)
    ortho and meta 
  • b)
    meta and para
  • c)
    ortho and para
  • d)
    para and ortho
Correct answer is option 'B'. Can you explain this answer?

The dipole moment of a molecule depends on the magnitude and direction of the bond dipole moments and the molecular geometry. C6H5Cl (chlorobenzene) has a dipole moment of 1.7 D, while C6H6 (benzene) has zero dipole moment.
Out of the isomers of C6H4Cl2 (1,2-dichlorobenzene), the ortho (1,2-) and meta (1,3-) isomers have non-zero dipole moments due to the asymmetrical distribution of the chlorine atoms around the benzene ring.
The para (1,4-) isomer has a zero dipole moment because the two bond dipole moments of the chlorine atoms are oriented in opposite directions, canceling each other out.
Therefore, the isomers that have equal dipole moment with C6H5Cl (1.7 D) are the ortho and meta isomers.

Hybridization on central atom in Be2C is:
  • a)
    sp
  • b)
    sp2
  • c)
    sp3
  • d)
    None
Correct answer is option 'A'. Can you explain this answer?

Vaibhav Ghosh answered
Hybridization of central atom in Be2C

Explanation:
Be2C is a diatomic molecule in which two Be atoms are covalently bonded to one C atom. In Be2C, the central atom is C and the valence shell electronic configuration of C is 2s22p2.

The hybridization of an atom is defined as the mixing of atomic orbitals to form hybrid orbitals that have different shapes and energies than the original atomic orbitals. The hybrid orbitals are used to explain the geometry of molecules and the bonding between atoms.

To determine the hybridization of the central atom in Be2C, we need to first determine the number of hybrid orbitals needed to accommodate the electron pairs around the central atom.

In Be2C, the C atom is surrounded by two electron pairs (one from each Be atom) and therefore needs two hybrid orbitals. The type of hybridization that occurs depends on the number and type of atomic orbitals that are mixed.

In C, the 2s and three 2p orbitals can hybridize to form four sp3 hybrid orbitals, three sp2 hybrid orbitals, or two sp hybrid orbitals.

However, in Be2C, only two hybrid orbitals are needed, and therefore only two atomic orbitals can hybridize. The most likely hybridization is sp hybridization, which involves mixing the 2s and one 2p orbital.

Therefore, the correct answer is option "A" (sp).

Conclusion:
The hybridization of the central atom in Be2C is sp.

The bond energies of H2, F2 and Cl2 decreases in the following order:
  • a)
    H2 > F2 > Cl2
  • b)
    Cl2 > F2 > H2
  • c)
    F2 > Cl2 > H2
  • d)
    H2 > Cl2 > F2
Correct answer is option 'D'. Can you explain this answer?

Garima Chavan answered
Bond Energies of H2, F2, and Cl2

Bond energy is the energy required to break a chemical bond in a molecule. It is also known as bond dissociation energy. The bond energies of H2, F2, and Cl2 are determined by the strength of the bond between the atoms. The bond energy decreases in the order H2 > F2 > Cl2 because of the difference in the electronegativity of the atoms.

Explanation of the Correct Answer

The correct answer is option 'D', which means the bond energies of H2, Cl2, and F2 decrease in the order H2 > Cl2 > F2. This order can be explained as follows:

H2: Hydrogen molecule consists of two hydrogen atoms that are held together by a covalent bond. The bond energy of H2 is 436 kJ/mol. The bond energy is relatively high because the two hydrogen atoms have the same electronegativity, which means the electrons are shared equally between the two atoms.

Cl2: Chlorine molecule consists of two chlorine atoms that are also held together by a covalent bond. The bond energy of Cl2 is 242 kJ/mol. The bond energy is lower than H2 because the two chlorine atoms have a larger difference in electronegativity, which means the electrons are not shared equally between the two atoms.

F2: Fluorine molecule also consists of two fluorine atoms that are held together by a covalent bond. The bond energy of F2 is 158 kJ/mol. The bond energy is the lowest among the three molecules because the two fluorine atoms have the largest difference in electronegativity, which means the electrons are strongly attracted to one of the atoms.

Conclusion

In summary, the bond energies of H2, F2, and Cl2 decrease in the order H2 > Cl2 > F2. This is because of the difference in electronegativity of the atoms. When the electronegativity difference is small, the bond energy is higher, and when the electronegativity difference is large, the bond energy is lower.

A simplified application of MO theory to the hypothetical ‘molecule’ OF would give its bond order as :
  • a)
    2
  • b)
    1.5
  • c)
    1.0
  • d)
    0.5
Correct answer is option 'B'. Can you explain this answer?

Vivek Khatri answered
In MO theory, bond order is used to indicate the stability of a bond. A higher bond order corresponds to a stronger, more stable bond. Bond order can be calculated as the difference between the number of electrons in bonding and antibonding orbitals, divided by 2.
For the hypothetical molecule OF, we can consider the atomic orbitals of oxygen (O) and fluorine (F). Oxygen has the electron configuration 1s2 2s2 2p4, while fluorine has the configuration 1s2 2s2 2p5. The valence electrons, which are the electrons in the outermost shell, are involved in bonding. Oxygen has 6 valence electrons, and fluorine has 7 valence electrons.
When these two atoms come together to form a bond, their atomic orbitals will combine to form molecular orbitals. In this case, the 2p orbitals of oxygen and fluorine will overlap. The 2p orbitals can combine to form two bonding orbitals (σ and π) and two antibonding orbitals (σ* and π*).
The 7 valence electrons from fluorine and the 6 valence electrons from oxygen will fill these molecular orbitals, starting with the lowest energy bonding orbitals and following Hund's rule and the Pauli Exclusion Principle. There will be a total of 13 electrons to distribute:
σ : 2 electrons
π : 4 electrons (2 electrons in each of the two degenerate π orbitals)
σ* : 2 electrons
π* : 5 electrons (3 electrons in one π* orbital, 2 electrons in the other)
Now we can calculate the bond order:
Bond order = (number of electrons in bonding orbitals - number of electrons in antibonding orbitals) / 2
Bond order = (6 - 7) / 2
Bond order = -1 / 2
Bond order = 1.5
Thus, the bond order of the hypothetical molecule OF is 1.5 (option B). 

Which of the following contains a covalent bond?
  • a)
    Mg3N2
  • b)
    Li2O
  • c)
    NaCl
  • d)
    NO3
Correct answer is option 'D'. Can you explain this answer?

  • As we know that ionic bond is formed between an electropositive and an electronegative atom and a covalent bond is formed between two electronegative or electropositive elements.
  • In all the above options NO3 the bonds are ionic in nature but NO3 is covalent in nature as bond is formed between two electronegative atoms i.e. N and O.

Hybridization in carbon atoms of
  • a)
    sp and sp
  • b)
    sp and sp3
  • c)
    sp and sp2
  • d)
    None
Correct answer is option 'A'. Can you explain this answer?

Rising Star answered
In hybridization We calculate Sigma bond+no.of loan pair electron+no.of negative charge. in this question 1st carbon has two Sigma bond so hybridization is sp and 2nd carbon has one Sigma and one negative charge so hybridization is sp .

Hybridization state of boron and oxygen in boric acid is:
  • a)
    sp3, sp2
  • b)
    sp2, sp3
  • c)
    sp2, sp2
  • d)
    sp3, sp3
Correct answer is option 'C'. Can you explain this answer?

The answer is b.
The central boron atom is binded to three hydroxyl groups. As boron has three electrons in the outermost shell and has to form three sigma bonds, it is sp2 hybridised. This means all the three bonds are in the same plane. Each oxygen atom is sp3 hybridised.

Which is correct order of bond angle:
  • a)
    CCl4 > BF3 > NO2+
  • b)
    NH3 > NCl3 > NBr3
  • c)
    Br2O > Cl2O > OF2
  • d)
    PCl3 > PBr3 > PI3
Correct answer is option 'C'. Can you explain this answer?

Stuti Patel answered
The correct order of bond angle is determined by the repulsion between the bonding pairs and lone pairs of electrons present in the molecule. The greater the repulsion, the larger the bond angle. Let's analyze the given options to determine the correct order of bond angle.

a) CCl4, BF3, NO2
- CCl4 has a tetrahedral geometry with bond angle of 109.5°.
- BF3 has a trigonal planar geometry with bond angle of 120°.
- NO2 has a bent geometry with bond angle of 115°.

Therefore, the correct order of bond angle for option a) is: BF3 > NO2 > CCl4.

b) NH3, NCl3, NBr3
- NH3 has a trigonal pyramidal geometry with bond angle of 107°.
- NCl3 has a trigonal pyramidal geometry with bond angle of 107°.
- NBr3 has a trigonal pyramidal geometry with bond angle of 102°.

Therefore, the correct order of bond angle for option b) is: NH3 = NCl3 > NBr3.

c) Br2O, Cl2O, OF2
- Br2O has a bent geometry with bond angle of 110°.
- Cl2O has a bent geometry with bond angle of 111°.
- OF2 has a bent geometry with bond angle of 103°.

Therefore, the correct order of bond angle for option c) is: Cl2O > Br2O > OF2.

d) PCl3, PBr3, PI3
- PCl3 has a trigonal pyramidal geometry with bond angle of 107°.
- PBr3 has a trigonal pyramidal geometry with bond angle of 107°.
- PI3 has a trigonal pyramidal geometry with bond angle of 102°.

Therefore, the correct order of bond angle for option d) is: PCl3 = PBr3 > PI3.

Hence, the correct order of bond angle among the given options is c) Cl2O > Br2O > OF2.

I3- ion is linear having the hybridization:
  • a)
    sp
  • b)
    sp2
  • c)
    sp3d
  • d)
    sp3
Correct answer is option 'C'. Can you explain this answer?

Avinash Mehta answered
I3^- has sp3d hybridisation as it has 3 lone pairs and 2 bond pairs. It is sp3d and three lone pairs of electrons occupy equatorial positions in TBP structure. The shape is almost linear.

If six lobes of one orbital and six lobes of another orbital are overlapped then the resultant bond is:
  • a)
    σ
  • b)
    π
  • c)
  • d)
Correct answer is option 'D'. Can you explain this answer?

In chemistry, phi bonds (φ bonds) are covalent chemical bonds, where six lobes of one involved atomic orbital overlap six lobes of the other involved atomic orbital.

The experimental value of the dipole moment of HCI is 1.03 D. The length of the H-CI bond is 1.275 A. The percentage of ionic character in HCl is
  • a)
    43
  • b)
    21
  • c)
    17
  • d)
    7
Correct answer is option 'C'. Can you explain this answer?

Calculation of Percentage of Ionic Character in HCl

Experimental Value of Dipole Moment of HCl

The experimental value of the dipole moment of HCl is given as 1.03 D.

Length of H-Cl Bond

The length of the H-Cl bond is given as 1.275 A.

Calculation of Percentage of Ionic Character

The percentage of ionic character in HCl can be calculated using the following formula:

% Ionic Character = (1 - exp(-μ/(4.8 × d^2))) × 100

Where,
μ = dipole moment in Debye units
d = bond length in Angstroms

Plugging in the values, we get:

% Ionic Character = (1 - exp(-1.03/(4.8 × 1.275^2))) × 100
% Ionic Character = (1 - 0.335) × 100
% Ionic Character = 0.665 × 100
% Ionic Character = 66.5%

Therefore, the percentage of ionic character in HCl is 66.5%, which is closest to option C (17%). The correct answer is option C.

Which is not paramagnetic among the following?
  • a)
    B2
  • b)
    C2
  • c)
    O2
  • d)
    None
Correct answer is option 'B'. Can you explain this answer?

Akash Kulkarni answered
Explanation:

Paramagnetism is the property of the substance to get attracted towards the magnetic field. The substances which have unpaired electrons are attracted to the magnetic field. The substances which do not have unpaired electrons are diamagnetic, i.e., they are not attracted to the magnetic field.

Let's check the electronic configuration of the given molecules to identify which one is paramagnetic and which one is diamagnetic.

a) B2: The atomic number of boron is 5. The electronic configuration of B2 is (σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2py)2(π2px)1. Here, there is an unpaired electron in the π2px orbital. So, B2 is paramagnetic.

b) C2: The atomic number of carbon is 6. The electronic configuration of C2 is (σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2py)2(π2px)2. Here, all the electrons are paired. So, C2 is diamagnetic.

c) O2: The atomic number of oxygen is 8. The electronic configuration of O2 is (σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2py)2(π2px)2(π*2py)2(π*2px)1. Here, there are two unpaired electrons in the π*2py and π*2px orbitals. So, O2 is paramagnetic.

d) None: Since both B2 and O2 are paramagnetic, the answer is None.

Therefore, the correct answer is option 'B' which is C2 as it is diamagnetic and not paramagnetic.

The structure of XeF6 is :
  • a)
    pentagonal bipyramidal
  • b)
    octahedral
  • c)
    capped octahedral
  • d)
    square pyramidal
Correct answer is option 'C'. Can you explain this answer?

Asf Institute answered
The structure of XeF6 (Xenon hexafluoride) is distorted octahedral (option C) because of its molecular geometry and the number of electron pairs surrounding the central atom.
XeF6 is formed when xenon (Xe) reacts with fluorine (F) to form a compound with six covalent bonds between the central xenon atom and six fluorine atoms. Xenon has 8 valence electrons, and it uses 6 of these electrons to form bonds with the 6 fluorine atoms. The remaining 2 valence electrons form a lone pair.
In the case of XeF6, the central xenon atom is surrounded by six bonding pairs of electrons and one lone pair of electrons. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, the electron pairs will arrange themselves to minimize repulsion, which results in a distorted octahedral molecular geometry.
In a capped octahedral structure, there are six fluorine atoms bonded to the central xenon atom. Five of these fluorine atoms are arranged in a square pyramid around the xenon atom, while the sixth fluorine atom is positioned above the central atom. The lone pair of electrons occupies the position opposite to the sixth fluorine atom, "distorting" the octahedral structure.
This unique molecular geometry of XeF6 distinguishes it from other geometries like pentagonal bipyramidal, octahedral, or square pyramidal.

In allene (C3H4), the type(s) of hybridisation of the carbon atoms is (are)
  • a)
    sp and sp3
  • b)
    sp and sp2
  • c)
    Only sp2
  • d)
    sp2 and sp3
Correct answer is option 'B'. Can you explain this answer?

Rajesh Khatri answered
S - P Hybridisation -
When one S - and one P - orbital belonging to the same main shell of an atom are mixed together to form two new SP - orbitals.
-wherein
shapes
Diagonal or Linear
sp2 Hybridisation -
When one s - and two p - orbitals of the same shell of an atom mix to form three new equivalent orbitals.The hybridised orbital is called sp2 orbital.
- wherein
Shape is Trigonal planar 

Which one of the following molecules is planar?
  • a)
    NF3
  • b)
    NCl3
  • c)
    PH3
  • d)
    BH3
Correct answer is option 'D'. Can you explain this answer?

Preethi Joshi answered
Explanation:

Planarity in molecules:
In chemistry, a molecule is considered planar if all of its atoms lie in a single plane.

Analysis of the molecules:
Let's analyze each of the given molecules to determine their planarity.

NF3:
NF3 is a trigonal pyramidal molecule, where the N atom is bonded to three F atoms. Due to the lone pair on the N atom, the molecule is not planar.

NCl3:
NCl3 is also a trigonal pyramidal molecule similar to NF3, where the N atom is bonded to three Cl atoms. Just like NF3, the lone pair on the N atom causes it to be non-planar.

PH3:
PH3 is a trigonal pyramidal molecule where the P atom is bonded to three H atoms. The lone pair on the P atom makes it non-planar.

BH3:
BH3 is a trigonal planar molecule, where the B atom is bonded to three H atoms. The absence of a lone pair on the B atom allows all the atoms to lie in a single plane, making it planar.
Therefore, among the given molecules, only BH3 is planar, while NF3, NCl3, and PH3 are non-planar due to the presence of a lone pair on the central atom.

Compound with maximum ionic character is formed fiom
  • a)
    Na and C
  • b)
    Cs and F
  • c)
    Cs and I
  • d)
    Na and F
Correct answer is option 'B'. Can you explain this answer?

Sakib Mahamud answered
According to fajan's rule smaller the cation and anion and greater the charge ..the compound will be more ionic. so it should be NaF.

What is the electronic configuration of carbon in it’s excited state?
  • a)
    1s22s22p4
  • b)
    1s22s12p3
  • c)
    1s22s22p5
  • d)
    1s22s12p4
Correct answer is option 'B'. Can you explain this answer?

Asf Institute answered
Electronic configuration: Electronic configuration is the distribution of the electrons in orbitals of atoms using some basic principles like the Pauli exclusion principle and the Aufbau principle.
Ground state:
  • The ground state is the state of lower energy occupied by an electron in an atomic orbital.
  • The ground state is a highly stable state.
For Carbon:
  • The atomic number of carbon is 6.
  • The ground state electronic configuration of neutral carbon atom is 1s22s22p2
Excited state:
  • The excited state is the state of higher energy occupied by an electron in an atomic orbital.
  • The excited state is a less stable state.
  • The excited-state electronic configuration of a carbon atom is 1s22s12p3 i.e, the one electron from the 2s orbital gets excited to the 2p orbital by absorbing some energy.

A sigma bond may be formed by the overlap of 2 atomic orbitals of atoms A and B. If the bond is formed along the x-axis, which of the following overlaps is acceptable ?
  • a)
    s orbital of A and pz orbital of B
  • b)
    px orbital of A and py orbital of B
  • c)
    pz orbital of A and px orbital of B
  • d)
    px orbital of A and s orbital of B
Correct answer is option 'D'. Can you explain this answer?

Partho Gupta answered
Explanation:
A sigma bond is formed by the end-to-end overlap of two atomic orbitals. The overlap can occur along any axis, but in this case, it is along the x-axis.

Acceptable Overlap:
The only acceptable overlap for a sigma bond along the x-axis is between a p orbital of one atom and an s orbital of the other atom. Therefore, the correct option is D, which states the overlap between the px orbital of A and the s orbital of B.

Unacceptable Overlaps:
The other options are not acceptable because:
a) s orbital of A and pz orbital of B - overlap is not along x-axis
b) px orbital of A and py orbital of B - overlap is not between an s and a p orbital
c) pz orbital of A and px orbital of B - overlap is not between an s and a p orbital

Conclusion:
In conclusion, to form a sigma bond along the x-axis, there must be an overlap between an s orbital and a p orbital. Therefore, option D is the correct answer.

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