Chemistry

Chemical Bonding and Molecular Structure

1,420 Questions

This section tests your knowledge of chemical bonding, molecular structure, and hybridization. It covers ionic and covalent bonds, octet rule exceptions, and molecular geometry. These chemistry questions are common in various competitive entrance examinations.

Ionic and covalent bondsHybridisation of elementsOctet rule exceptionsMolecular geometryIntermolecular forces

Chemical Bonding and Molecular Structure Questions

Multiple choice

Assertion (A) Among the alkali metals, lithium salts exhibit the least electrical condutance in aqueous solutions.Reason (R) Smaller the radius of the hydrated cation, lower is the electrical conductance in aqueous solutions.

  1. Both (A) and (R) are true and (R) is the correct explanation of (A).

  2. Both (A) and (R) are true but (R) is not the correct explanation of (A).

  3. (A) is true but (R) is false.

  4. (A) is false but (R) is true.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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Multiple choice

Which of the following is a molecule of an element?

  1. Ozone

  2. Sugar

  3. Sodium chloride

  4. Salt
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An element of a pure substance contains only one kind of atom. Molecule is a group of two or more atoms that are chemically bonded together, i.e. tightly held together by attractive forces. Atoms of the same element or different elements can join to form molecules. The same type of atoms constitutes the molecules of an element. A molecule of ozone (O3) consists of three atoms of oxygen and thus, it is a molecule of an element. Sugar (C12H22O11), sodium chloride (NaCl) and salt (NaCl) consist of atoms of different elements joined together in definite proportions. Thus, they are molecules of compounds.

Multiple choice

Which of the following schemes of transfer of electrons shows 'Z' scheme?

  1. PS II______PS I _NADP+H+_________NADP+

  2. PS I______PS II _NADP+H+_________NADP+

  3. PS I______PS II _NADP+_________NADP+H+

  4. PS II______PS I _NADP+_________NADP+H+

  5. NADP+_______NADP+H+PS II______PS I
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yes, it is correct. This whole scheme of transfer of electrons, starting from the PS II, uphill to the accepter, down the electron transport chain to PS I, excitation of electrons, transfer to another accepter, and finally down hill to NADP+ causing it to be reduced to NADPH+H+ is called the Z scheme.

Multiple choice

Which of the following are used as intercalating agents in chemical mutation?

  1. Acridine orange, proflavin and ethidium bromide

  2. Nitrosoguanidine, methyl methanesulfonate and ethyl methanesulfonate

  3. NAAAF

  4. Peroxides

  5. Aminopurine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acridine orange, proflavin and ethidium bromide are flat, multiple ring molecules which react with DNA bases and insert between them. This insertion creates a stretching in the DNA duplex and the DNA polymerase is fooled into inserting an extra base opposite an intercalated molecule. The result is that intercalating agents cause frameshifts.

Multiple choice

Which of the following has the lowest electro negativity?

  1. F

  2. He

  3. Hg

  4. Cl
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Helium has the lowest electronegativity because it is a noble gas and noble gases are chemically very stable as they have the maximum number of valence electrons that their outer shell can hold. Thus, the noble gas atom, being electrically neutral, would not be able to exert much attractive force on free-ranging electrons, i.e. low electronegativity.

Multiple choice

Which of the following statements is correct?

  1. X– ion is larger in size than x– atom.

  2. X+ ion is larger in size than x– atom.

  3. X+ ion is larger in size than x– ion.

  4. X+ and X– ions are equal in size.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The size of anion is always greater than the corresponding atom. Thus, only statement 1 is correct.