Class 11 Chemistry - Chapter Chemical Bonding and Molecular Structure NCERT Solutions | What is the total number of sigma and pi

What is meant by the term bond order? Calculate the bond order of: N₂, O₂,O₂⁺,and O₂^-.

Use molecular orbital theory to explain why the Be2 molecule does not exist.

Explain the formation of H₂ molecule on the basis of valence bond theory.

Compare the relative stability of the following species and indicate their magnetic properties:

O₂,O₂⁺,O₂^- (superoxide), O₂^2-(peroxide)

Describe the hybridisation in case of PCl₅. Why are the axial bonds longer as compared to equatorial bonds?

Which out of NH₃ and NF₃ has higher dipole moment and why?

Explain why BeH₂ molecule has a zero dipole moment although the Be–H bonds are polar.

Discuss the shape of the following molecules using the VSEPR model:

BeCl₂, BCl₃, SiCl₄, AsF₅, H₂S, PH₃

Write Lewis symbols for the following atoms and ions:

S and S2–; Al and Al3+; H and H–

Draw the Lewis structures for the following molecules and ions: H2S, SiCl4, BeF2, , HCOOH

How do you account for the formation of ethane during chlorination of methane?

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

What are the common physical and chemical features of alkali metals?

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH₂PO₄

(b) NaHSO₄

(c) H₄P₂O₇

(d) K₂MnO₄

(e) CaO₂

(f) NaBH₄

(g) H₂S₂O₇

(h) KAl(SO₄)₂.12 H₂O

What is the basic theme of organisation in the periodic table?

Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

A large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping but you find an abundance of phytoplankton. Suggest a reason for the fish kill.

Which of the following are isoelectronic species i.e., those having the same number of electrons?

Na⁺, K⁺, Mg²⁺, Ca²⁺, S^2–, Ar

Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Why?

A sample of drinking water was found to be severely contaminated with chloroform, CHCl₃, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).

(i) Express this in percent by mass.

(ii) Determine the molality of chloroform in the water sample.

Pressure is determined as force per unit area of the surface. The SI unit of pressure, Pascal is as shown below:

1Pa = 1N m^–2

If mass of air at sea level is 1034 g cm^–2, calculate the pressure in Pascal.

What causes the temporary and permanent hardness of water?

Justify that the following reactions are redox reactions:

(a) CuO_(s) + H_2(g) → Cu_(s) + H₂O_(g)

(b) Fe₂O_3(s) + 3CO_(g) → 2Fe_(s) + 3CO_2(g)

(c) 4BCl_3(g) + 3LiAlH_4(s) → 2B₂H_6(g) + 3LiCl_(s) + 3 AlCl_{3 (s)}

(d) 2K_(s) + F_2(g) → 2K⁺F^– _(s)

(e) 4 NH_3(g) + 5 O_2(g) → 4NO_(g) + 6H₂O_(g)

A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57μm. Calculate the rate of emission of quanta per second.

Draw the cis and trans structures of hex-2-ene. Which isomer will have higher b.p. and why?

Complete the following reactions: