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The atomic mass of Sr as predicted according to the Dobereiner's law of triads in the triad Ca(Z=40), Sr, Ba(Z=137)is ___.

• 80

• 88

• 100

• 85

Element ‘X’ forms a chloride with the formula XCl2, which is a solid with high melting point. X would most likely be in the same group of the periodic table as:

• (a) Si

• (b) Mg

• (c) Al

• (d) Na

3.12. Consider the following species :

N3–, O2–, F–, Na+, Mg2+and Al3+

(b) Arrange them in the order of increasing ionic radii.

• < F– < O2- < N3-<Al3+ < Mg2+ < Na+

• Al3+ < Mg2+ < Na+ < F– < O2- < N3-

• Al3+ <F - < Na+ < Mg2+ < O2- < N3-

• N3 - < O2- < Al3+ < Mg2+ < Na+ < F–

In the modern periodic table, the period indicates the value of

• (a)atomic numberr

• (b) mass number

• (c) principal quantum numbe

• (d) azimuthal quantum number

Which of the following statements related to the modem periodic table is incorrect?

• (a) The p-block has 6 columns because a maximum of 6 electrons can occupy all the orbitals in a p-shell.

• (b) The d-block has 8 columns because a maximum of 8 electrons can occupy all the orbitals in a d-subshell.

• (c) Each block contains a number of columns equal to the number of electrons that can occupy that subshell.

• (d) The block indicates the value of azimuthal quantum number (l) for the last subshell that received electrons in building up the electronic configuration.

Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following factors does not affect the valence shell?

• (a) Valence principal quantum number (n)

• (b) Nuclear charge (Z )

• (c) Nuclear mass

• (d) Number of core electrons.

The size of isoelectronic species — F–, Ne and Na+ is affected by

• (a) nuclear charge (Z)

• (b) valence principal quantum number (n)

• (c) electron-electron interaction in the outer orbitals

• (d) none of the factors because their size is the same

Which one of the following statements is incorrect in relation to ionization enthalpy?

• (a) Ionization enthalpy increases for each successive electron.

• (b) The greatest increase in ionization enthalpy is experienced on the removal of an electron from core noble gas configuration.

• (c) End of valence electrons is marked by a big jump in ionization enthalpy.

• (d) Removal of electrons from orbitals bearing lower n value is easier than from orbital having higher n value

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

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