Chemistry : Chemical Bonding and Molecular Structure

The decreasing values of bond angles from NH3 (106^o ) to SbH₃ (101^o ) down group-15 of the periodic table is due to

• increasing bp-bp repulsion

• increasing p-orbital character in sp³

• decreasing lp-bp repulsion

• decreasing lp-bp repulsion

Which one of the following species is diamagnetic in nature?

• He₂⁺

• H₂

• H₂⁺

• H₂⁺

The number and type of bonds between two carbon atoms in calcium carbide are

• One sigma, one pi

•  One sigma, two pi

• Two sigma, one pi

• Two sigma, one pi

Of the following sets which one does NOT contain isoelectronic species?

• PO^-3₄,SO₄^-2, ClO₄^-

• CN^-, N₂, C₂^-2

• SO₃^-2, CO₃^-2,NO₃^-

• SO₃^-2, CO₃^-2,NO₃^-

The structure of diborane (B₂H₆) contains

• four 2c-2e bonds and two 3c-2e bonds

• two 2c-2e bonds and four 3c-2e bonds

• two 2c-2e bonds and two 3c-3e bonds

• two 2c-2e bonds and two 3c-3e bonds

The correct order of bond angles (smallest first) in H₂S, NH₃, BF₃ and SiH₄ is

• H₂S < SiH₄ < NH₃ < BF₃

• H₂S < NH₃ < BF₃ < SiH₄

• NH₃ < H₂S < SiH₄ < BF₃

• NH₃ < H₂S < SiH₄ < BF₃

Which one the following sets of ions represents the collection of isoelectronic species?

• K⁺ , Ca²⁺, Sc³⁺, Cl^-

• Na⁺ , Mg²⁺, Al³⁺, Cl^-

• K⁺ , Cl^- , Mg²⁺, Sc³⁺

• K⁺ , Cl^- , Mg²⁺, Sc³⁺

Among Al₂O₃, SiO₂, P₂O₃ and SO₂ the correct order of acid strength is

• SO₂ < P₂O₃ < SiO₂ < Al₂O₃

• Al₂O₃ < SiO₂ < P₂O₃ < SO₂

• Al₂O₃ < SiO₂ < SO₂ < P₂O₃

• Al₂O₃ < SiO₂ < SO₂ < P₂O₃

The bond order in NO is 2.5 while that in NO+ is 3. Which of the following statements is true for these two species?

• Bond length in NO⁺ is greater than in NO

• Bond length is unpredictable

• Bond length in NO⁺ in equal to that in NO

• Bond length in NO⁺ in equal to that in NO

The states of hybridization of boron and oxygen atoms in boric acid (H₃BO₃) are respectively

• sp² and sp²

• sp³ and sp³

• sp³ and sp²

• sp³ and sp²