Periodic Table and Periodicity in Properties NIOS Intext Questions With Answer

National Institute of Open Schooling (NIOS)
Sr. Secondary, Module-2
Lession-3: Periodic Table and Periodicity in Properties NIOS Intext Questions With Answer

INTEXT QUESTIONS 3.1

1. Classify the elements of group 14, 15 and 16 into metals, non-metals and metalloids.

Answer:

Metals	Non-Metals	Metalloids
Sn, Pb	C	Si, Ge
Sb, Bi	N, P	As
Te, Po	O, S	Se

2. Compare the metallic character of aluminium and potassium.

Answer: Potassium is more metallic than aluminum.

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3. Name the group number for the following type of clements i. Alkaline earth metals ii. Alkali metals iii. Transition metals iv. Halogens v. Noble gases.

Answer: i. 2
ii. 1
iii. 3 - 12
iv. 17
v. 18

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4. Name five man made elements.

Answer: Np, Lr, No, Rf, Hs.

INTEXT QUESTIONS 3.2

1. Write the names of the elements with atomic numbers 105, 109, 112, 115 according to IUPAC nomenclature.

Answer: 105: Unnilpentium
109: unnilennium
112: Ununbium
115: Ununpentium

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2. Arrange the following in the order of increasing size Na⁺, Al³⁺, O^2–, F^–

Answer: Al³⁺ Na⁺ F^– O^2–

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3. How does the size of atoms vary from left to right in a period and on descending a group in the periodic table?

Answer: The atomic size decreases from left to right across a period and increases on moving down the group.

INTEXT QUESTIONS 3.3

1. What is the correlation between atomic size and ionization enthalpy.

2. Which species, in each pair is expected to have higher ionization enthalpy.
i. ₃Li, ₁₁Na
ii. ₇N, ₁₅P
iii. ₂₀Ca, ₁₂Mg
iv. ₁₃Al, ₁₄Si
v. ₁₇Cl, ₁₈Ar
vi. ₁₈Ar, ₁₉K
vii. ₁₃Al, ₆C

Answer: i. ₃Li
ii. ₇N
iii. ₁₂Mg
iv. ₁₄Si
v. ₁₈Ar
vi. ₁₈Ar
vii. ₆C

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3. Account for the fact that there is a decrease in first ionization enthalpy from Be to B and Mg to Al.

Answer: The electronic configureation of Be is 1s²2s² whereas that of B is 1s²2s²2p¹. In case of Be, the electron is to be removed from completely filled s orbital whereas in case of B it is to be removed from a singly occupied p orbital. Fully-filled orbitals are more stable. Hence, ionization enthalpy decreases from Be to B. Similarily it decreases from Mg to Al.

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4. Why is the ionization enthalpy of the noble gases highest in their respective periods?

Answer: The noble gases have fully filled shells and are stable. Hence, they have the highest ionization enthalpies in their respective periods.

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5. Name the most electronegative element.

Answer: Fluorine

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