Chemistry Class-11: Chapter – 3. Classification of Elements and Periodicity in Properties-Part – 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question: 28

Among the elements B, Al, C and Si,

(i) Which element has the highest first ionization enthalpy?

(ii) Which element has the most metallic character? Justify your answer in each case.

Answer:

(i) Carbon

(ii) Aluminium

Question:

Write four characteristic properties of p-block elements.

Answer:

Question: 30

Choose the correct order of atomic radii of fluorine and neon (in pm) out of the options given below and justify your answer.

(i)

(ii)

(iii)

(iv)

Answer: (i)

Question: 31

Illustrate by taking examples of transition elements and non-transition elements that oxidation states of elements are largely based on electronic configuration.

Question: 32

Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However, oxygen has lower ionization enthalpy than nitrogen. Explain.

Answer:

The outermost electronic configuration of nitrogen is very stable because p-orbital is half filled. Addition of extra electron to any of the 2p orbital requires energy.

Oxygen has electrons in orbitals and acquires stable configuration i.e.. , configuration after removing one electron.

Question: 33

First member of each group of representative elements (i.e.. , s and p-block elements) shows anomalous behavior. Illustrate with two examples.

Question: 34

p-Block elements form acidic, basic and amphoteric oxides. Explain each property by giving two examples and also write the reactions of these oxides with water.

Question: 35

How would you explain the fact that first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?

Answer:

After removing 1 electron from the sodium atom the ion formed acquires the configuration of inert gas, neon. The second electron is removed from one of the 2p-orbitals which are completely filled i.e.. , have a total of 6 electrons and are closer to the nucleus.

Question: 36

What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.

Question: 37

Arrange the elements N, P, O and S in the order of-

(i) increasing first ionization enthalpy.

(ii) increasing non-metallic character.

Give reason for the arrangement assigned.

Answer:

(i)

(ii)

Question: 38

Explain the deviation in ionization enthalpy of some elements from the general trend by using Fig. 3.2.

Ionization Enthalpy

Question: 39

Explain the following:

(a) Electronegativity of elements increase on moving from left to right in the periodic table.

(b) Ionization enthalpy decrease in a group from top to bottom?

Answer:

(a) Decrease in size of atom and increase in nuclear charge.

(b) Increase in atomic size.

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