Classification of Elements and Periodicity in Properties

Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture? 

• The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic number down the group

• In both the alkali metals and the halogens the chemical reactivity decreases with increase in atomic number down the group

• Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens

• Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens

In a multi-electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic acid and electric fields?

(a) n = 1, l = 0, m = 0
(b) n = 2, l = 0, m = 0
(c) n = 2, l = 1, m = 1
(d) n = 3, l = 2, m = 1
(e) n = 3, l = 2, m = 0

• (a) and (b)

• (b) and (c)

• (c) and (d)

• (c) and (d)

In which of the following arrangements the order is NOT according to the property indicated against it?

• Al³⁺ < Mg²⁺ < Na⁺ < F^- Increasing ionic size

• B < C < N < O Increasing first ionization enthalpy

• I < Br < F < Cl Increasing electron gain enthalpy (with negative sign)

• I < Br < F < Cl Increasing electron gain enthalpy (with negative sign)

Which of the following statements in relation to the hydrogen atom is correct?

• 3s orbital is lower in energy than 3p orbital

• 3p orbital is lower in energy than 3d orbital

• 3s and 3p orbitals are of lower energy than 3d orbital

• 3s and 3p orbitals are of lower energy than 3d orbital

Which one the following ions has the highest value of ionic radius?

• Li⁺

• F^-

• O^2-

• O^2-

Which of the following atoms should have the highest I^st electron affinity?

• F

• O

• N

• C

The decreasing order of basic character of K₂O, BaO, CaO and MgO is

• K₂O > BaO > CaO > MgO

• K₂O > CaO > BaO > MgO

• MgO > BaO > CaO > K₂O

• MgO > CaO > BaO > K₂O

Among Be, B, Mg and Al, the second ionisation potential is maximum for

• B

• Be

• Mg

• Al

In case of heteronuclear diatomics of the type AB, where A is more electronegative than B, bonding molecular orbital resembles the character of A more than that of B. The statement

• is false

• is true

• cannot be evaluated since data is not sufficient

• is true only for certain systems

In borax the number of B-O-B links and B-OH bonds present are, respectively

• five and four

• four and five

• three and four

• five and five