Class 11 Chemistry - Chapter Environmental Chemistry NCERT Solutions | What would have happened if the greenhou

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

What are the harmful effects of photochemical smog and how can they be controlled?

Write down the reactions involved during the formation of photochemical smog.

Explain tropospheric pollution in 100 words.

What are the reactions involved for ozone layer depletion in the stratosphere?

Statues and monuments in India are affected by acid rain. How?

What do you mean by green chemistry? How will it help decrease environmental pollution?

What is smog? How is classical smog different from photochemical smog?

What do you mean by ozone hole? What are its consequences?

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.

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?

Explain the formation of a chemical bond.

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 giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant.

Elements of group 14

(a) exhibit oxidation state of +4 only

(b) exhibit oxidation state of +2 and +4

(c) form M^2-and M⁴⁺ion

(d) form M²⁺and M⁴⁺ions

Explain why is there a phenomenal decrease in ionisation enthalpy from carbon to silicon?

How much energy is required to ionise a H atom if the electron occupies n = 5 orbit? Compare your answer with the ionization enthalpy of H atom (energy required to remove the electron from n =1 orbit).

Consider the reactions:

(a) 6CO_2(g) + 6H₂O_(l) → C₆H₁₂O_6(aq) + 6O_2(g)

(b) O_3(g) + H₂O_2(l) → H₂O_(l) + 2O_2(g)

Why it is more appropriate to write these reactions as:

(a) 6CO_2(g) + 12H₂O_(l) → C₆H₁₂O_6(aq) + 6H₂O_(l) + 6O_2(g)

(b) O_3(g) + H₂O_2(l) → H₂O_(l) + O_2(g) + O_2(g)

Also suggest a technique to investigate the path of the above (a) and (b) redox reactions.

Calculate the wavelength of an electron moving with a velocity of 2.05 × 10⁷ ms^–1.

Calculate the atomic mass (average) of chlorine using the following data:

Equilibrium constant, Kc for the reaction

N2 (g) + 3H2 (g) ↔ 2NH₃ (g) at 500 K is 0.061

At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol L^–1 N₂, 2.0 mol L^–1 H₂ and 0.5 mol L^–1 NH₃.

Is the reaction at equilibrium?

If not in which direction does the reaction tend to proceed to reach equilibrium?

Write structures of all the alkenes which on hydrogenation give 2-methylbutane.

At 473 K, equilibrium constant K_c for decomposition of phosphorus pentachloride, PCl₅ is 8.3 ×10^-3. If decomposition is depicted as,

PCl₅ (g) ↔  PCl₃ (g) + Cl₂ (g)          Δ_rH⁰ = 124.0 kJ mol^–1

(a) write an expression for Kc for the reaction.

(b) what is the value of Kc for the reverse reaction at the same temperature ?

(c) what would be the effect on K_c if (i) more PCl5 is added (ii) pressure is increased (iii) the temperature is increased ?