Class 11 Chemistry - Chapter Classification of Elements and Periodicity in Properties NCERT Solutions | Why do elements in the same group have s

Write the general outer electronic configuration of s-, p-, d- and f- block elements.

Considering the elements B, Al, Mg, and K, the correct order of their metallic character is:
(a) B > Al > Mg > K
(b) Al > Mg > B > K
(c) Mg > Al > K > B
(d) K > Mg > Al > B

What is the basic difference between the terms electron gain enthalpy and electronegativity?

What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.

(i) F^–

(ii) Ar

(iii) Mg²⁺

(iv) Rb⁺

Considering the elements B, C, N, F, and Si, the correct order of their non-metallic character is:
(a) B > C > Si > N > F
b) Si > C > B > N > F
(c) F > N > C > B > Si
d) F > N > C > Si > B

Assign the position of the element having outer electronic configuration

(i) ns² np⁴ for n = 3 (ii) (n - 1)d² ns² for n = 4, and (iii) (n - 2) f⁷ (n - 1)d¹ ns² for n = 6, in the periodic table.

How does atomic radius vary in a period and in a group? How do you explain the variation?

Use the periodic table to answer the following questions.
(a) Identify an element with five electrons in the outer subshell.
(b) Identify an element that would tend to lose two electrons.
(c) Identify an element that would tend to gain two electrons.
(d) Identify the group having metal, non-metal, liquid as well as gas at the room temperature.

Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is:
(a) F > Cl > O > N
(b) F > O > Cl > N
(c) Cl > F > O > N
(d) O > F > N > Cl

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

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

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

Why does benzene undergo electrophilic substitution reactions easily and nucleophilic substitutions with difficulty?

Describe the shapes of BF₃ and  BH₄^-. Assign the hybridisation of boron in these species.

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

(a) PCl₅ (g) ↔ PCl₃ (g) + Cl₂ (g)

(b) CaO (s) + CO₂ (g) ↔ CaCO₃ (s)

(c) 3Fe (s) + 4H₂O (g) ↔ Fe₃O₄ (s) + 4H₂ (g)

What is the concentration of sugar (C₁₂H₂₂O₁₁) in mol L^–1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?

Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?

Give the number of electrons in the species , H2 and

Dual behaviour of matter proposed by de Broglie led to the discovery of electron microscope often used for the highly magnified images of biological molecules and other type of material. If the velocity of the electron in this microscope is 1.6 × 10⁶ ms^–1, calculate de Broglie wavelength associated with this electron.

Do you observe any soil pollution in your neighbourhood? What efforts will you make for controlling the soil pollution?

The concentration of hydrogen ion in a sample of soft drink is 3.8 × 10^–3 M. what is its pH?

The reaction of cyanamide, NH₂CN (s), with dioxygen was carried out in a bomb calorimeter, and ΔU was found to be –742.7 kJ mol^–1 at 298 K. Calculate enthalpy change for the reaction at 298 K.

NH₂CN(g) + 3/2 O₂(g)  →  N₂(g) + CO₂(g) + H₂O(l)