Physical Properties of Boron Family

Q. The correct order of atomic radii in group 13 element is

1. $B<Ga<Al<Tl<In$
2. $B<Al<In<Ga<Tl$
3. $B<Ga<Al<In<Tl$
4. $B<Al<Ga<In<Tl$

Q.

Write main differences between the properties of white phosphorus and red phosphorus.

Q.

The color of KMnO4 is due to

Q.

Hybridization in [Co(NH3)6] is ?

Q. The compound that is not a Lewis acid is :

1. $B{F}_3$
2. $AlC{l}_3$
3. $BeC{l}_2$
4. $SnC{l}_4$

Q.

The chemical properties of an element are determined by the number of electrons in its atom, which in turn is determined by the number of protons.

So can we say that the chemical properties of an element are determined by the number of protons?

Q.

The hexaquo manganese(II) ion contains five unpaired electrons, while the hexacyanoion contains only one unpaired electron. Explain using Crystal Field Theory.

Q.

Considering the parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration enthalpy, compare the oxidising power of F₂ and Cl₂.

Q.

Which of the following is an electrophilic reagent ?

1) ROH 2) BF₃ 3)NH₃ 4)RO^-

Q. Boron has an extremely high melting point because of:

1. the strong van der waals forecs between its atoms
2. allotropy
3. due to very strong crystalline lattice.
4. its ionic crystal structure

Q. In the preparation of $AgI$ sol, the excess of $AgN{O}_3$, is added to potassium iodide solution. The particles of the sol will acquire –

1. Negative charge
2. Positive charge
3. No charge
4. Unpredictable

Q.

Distinguish between intrinsic and extrinsic semiconductors.

Q.

The density of elements of 3d series across a period:

1. Decreases from left to right across a period

2. Remain constant throughout

3. Increases from left to right across a period

4. First increases then decreases

Q.

Why do transition elements have high enthalpy of hydration?

Q. Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Fluorine forms one oxoacid.
Reason R: Fluorine has smallest size amongst all halogens and is highly electronegative.
In the light of the above statements, choose the most appropriate answer from the option given below.

Q. Which one of the following is most stable ?

1. $A{l}^{+}$
2. $G{a}^{+}$
3. $I{n}^{+}$
4. $T{l}^{+}$

Q.

$Cr{O}_4^{2-}$ is a strong oxidizing agent but $Mn{O}_4^{2-}$ is not. Explain why?

Q.

Which of the following gives the correct increasing order of the atomic radii of $\mathrm{O},\mathrm{F}\mathrm{and}\mathrm{N}$?

1. $\mathrm{O},\mathrm{F},\mathrm{N}$

2. $\mathrm{N},\mathrm{F},\mathrm{O}$

3. $\mathrm{O},\mathrm{N},\mathrm{F}$

4. $\mathrm{F},\mathrm{O},\mathrm{N}$

Q. Which one of the following is a correct set for $Si{O}_2$ ?

1. Trigonal planar
2. Linear
3. Tetrahedral
4. Angular

Q.

The main factor responsible for weak acidic nature of B-F bonds in BF3 is -

1. Large electronegativity of F

2. Three centred two electron bonds in BF3

3. pp­- dp back bonding

4. pp- pp back bonding

Q. Following the transition elements, (IE)1 drops abruptly in Ga, In and Tl. This is due to :-
1. Decrease in effective nuclear charge.
2. Increases in atomic radius.
3. Removal of an electron from the singly occupied np orbitals of higher energy than the ns-orbitals of Zn, Cd and Hg.
4. None is correct.
​​​​With explanation.

Q. Which of the following elements of the Boron Family is non-metallic in nature?

1. Ga
2. In
3. B
4. Tl

Q.

PbX_{​​​​2} is more stable than PbX_{​​​​4}. Why?

Q. $Zr$ (Z=40) and $Hf$ (Z=72) have similar atomic and ionic radii because of :

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Q.

Hydrogen can be made to use to form helium at

1. Low pressure and high temperature

2. High pressure and high temperature

3. Low pressure and low temperature

4. High pressure and low temperature

Q.

Melting point of d block elements across a period:

1. Does not change on moving from left to right.

2. Increases from left to right

3. Increases to a maximum at d⁵ and then decreases with increase of atomic number.

4. Deceases from left to right

Q. Boron forms covalent compounds due to :

1. higher ionisation enthalpy
2. lower ionisation enthalpy
3. small size
4. large size

Q. Explain the allotropes of boron.

Q.

An element belongs to 3rd period and group 13 of the periodic table. Which of the following properties will be shown by the element?
(a) Good conductor of electricity (b) liquid, metallic (c) solid , metallic (d) Solid, non-metallic

Q. The correct decreasing order of basic strength in the given compound is:

1. $a>b>c$
2. $a>c>b$
3. $c>b>a$
4. $c>a>b$