Anamolous Behaviour of Boron

Q. Which has maximum covalent character?
1. NaCl 2.SiCl4 3.AlCl3 4.MgCl2

Isn't SiCl4 the answer? Because covalent character is inversely proportional to polarisation and polarisation is inversely proportional to size of the atom. Since out if these, Si is the largest in is have the least polarisation and thus will result in the highest covalent character.

is this correct? If not, why not?

Q.

Molecules are of three types: Molecule of an atom, Molecule of an element and Molecule of a compound.

1. True
2. False

Q.

Is Silicon is a metal, metalloid or nonmetal explain?

Q. The Effective Atomic Number (EAN) of nickel in Ni$\left(C{O}_4\right)$ is:

Q.

Which has more ionisation energy- Nitrogen or Oxygen?

Q. The difference in the oxidation numbers of the two types of sulphur atoms in $N{a}_2{S}_4{O}_6$ is:

Q.

Give examples of oxides that are neutral and acidic oxide.

Q.

Which of the following electronic configuration an atom has the lowest ionization enthalpy?

1. 1s² 2s² 2p³

2. 1s² 2s² 2p⁶ 3s¹

3. 1s² 2s² 2p⁶

4. 1s² 2s² 2p⁵

Q.

Give two examples to show the anomalous behaviour of fluorine.

Q.

${\mathrm{BCl}}_3$ does not exist as dimer but ${\mathrm{BH}}_3$ exists as dimer $\left({\mathrm{B}}_2{\mathrm{H}}_6\right)$. Explain Why?

Q.

Convert Methane into Chloroform.

Q.

Is Chlorine a Good Nucleophile?

Q.

Assertion (A): Noble gases have very low boiling points.

Reason (R): All noble gases have a general electronic configuration of $\text{n}{s}^2\text{n}{p}^6$ (except He).

Q.

State three reasons that magnesium is a metal.

Q. $BC{l}_3$ does not exist as a dimer but $B{H}_3$ exists as a dimer because:

1. Chlorine is more electronegative than hydrogen
2. Large sized chlorine atoms do not fit in between the boron atoms whereas small sized hydrogen atoms fit in between the boron atoms
3. None of the above
4. There is a $p\pi -p\pi$ back bonding in $BC{l}_3$ but $B{H}_3$ does not contain such bonds

Q.

Why are the reactions involving deuterium slower than that of protium?

Q. Which of the following statements is not correct regarding halides of group 13 elements?

1. Boron halides act as Lewis acids
2. The tendency to form $p\pi -p\pi$ bond is less in $B{F}_3$ than in $BC{l}_3$
3. None of the above
4. $B{F}_3$ is a weaker Lewis acid than $BC{l}_3$

Q.

Boron form covalent compound due to

1. Both (a) and (c)

2. Small size

3. Lower ionization energy

4. Higher ionization energy

Q. What are true peroxide

Q. Boron compounds behave as Lewis acids because of their

1. Acidic nature
2. Covalent nature
3. Vacant orbital
4. Ionization property

Q. For the energy levels in an atom which one of the following statements is correct?

1. The 4s sub energy level is at a higher energy than the 3d sub energy level
2. The M energy level can have maximum of 32 electrons
3. The second principal energy level can have four orbitals and contain a maximum of 8 electrons
4. The 5th main energy level can have maximum of 58 electrons

Q.

An atom of an element has electronic configuration $2,3$. It forms a compound with an element having the electronic configuration $2,7$. Identify the false statement regarding the compound.

1. It possesses contracted octet.

2. It can act as an electron acceptor.

3. There are three lone pairs on a non-metal atom.

4. It is an unstable molecule.

Q. The appearance of color in solid alkali metal halides is generally due to

1. Frenkel defect
2. Interstitial defects
3. Schottky defect
4. F centres

Q. The tendency of BF${}_3$, BCl${}_3$ and BBr${}_3$ to behave as Lewis acid decreases in the sequence is:

1. BCl${}_3$ > BF${}_3$ > BBr${}_3$
2. BBr${}_3$ > BCl${}_3$ > BF${}_3$
3. BBr${}_3$ > BF${}_3$ > BCl${}_3$
4. BF${}_3$ > BCl${}_3$ > BBr${}_3$

Q. Why dont acids have lone pair around the central atom?

Q. 13. (Co(ox)2(OH)2)- Beside, having low field ligand why it form low spin complex?

Q.

Which of the following elements gain one electron more readily in comparison to other elements of the same group?

1. S(g)

2. N(g)

3. O(g)

4. Cl(g)

Q.

Give reason:

(a) Alkali metals are kept in an inert solvent.

(b) Alkali metals and halogens do not occur free in nature.

(c) Alkali and alkaline earth metal compounds usually form an electrovalent compound.

(d) Inert gases do not form compounds.

Q.

What is the heaviest alkali metal?

Q.

Lithium, Sodium, and Potassium are known as________ metals. These metals are ________ as they have valency 1.