Physical Properties of Boron Family

Q. The structures of $BC{l}_3$ and $AlC{l}_3$ in their liquid states are, respectively:

1. Monomer and monomer
2. Dimer and dimer
3. Dimer and monomer
4. Monomer and dimer

Q.

Distinguish between n-type and p-type semiconductors

Q. 4. How many electrons should X2H4 liberate so that in the new compound X shows oxidation number of -1/2 ( E.N. X > H) 1) 10 2) 4 3) 3 4) 2

Q. Crystalline boron reacts with air at high temperatures.

1. True
2. False

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

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

Q.

Structure of $I{F}_4^{+}$ and hybridization of iodine in this structure are

1. , Irregular tetrahedral

2. , Linear

3. , T-shaped

4. , Octahedral

Q.

Mg₂C₃ reacts with water forming propyne gas.ions has

1. Two sigma and one pi bond

2. Two sigma and two pi bonds

3. Two sigma and three pi bonds

4. Three sigma and one pi bond

Q. InH2SO4 there is a co-ordination bond between sulphur and oxygen but in oxy-acids of sulphur in H2SO4 there is a double bond between sulphur and oxygen why

Q. Which of the following has highest first ionization enthalpy?

1. B

2. Si

3. Al

4. C

Q. 44. Which is correct 1. NO>N2O (bond length of N-O) 2. N203>N2O5 (acidic strength) 3. N203>N204 (O-N-O bond angle) 4. No2=n205 (O-N-O bond angle)

Q. 19. Mg forms Mg(ll) because of :- 1) The oxidation state of Mg is +2 2) Difference between I. P1 and I. P2 is greater than 16.0 eV 3) There is only one electron in the outermost energy level of Mg 4) Difference between I. P1 and I. P2 is less than 11eV

Q. 24. Which of this following has least bond angle option are (1) CH4 (2) BH3 (3) H2O (4) NH3

Q. explain it separating hydrogen isotope of mass number 2 by physical method

Q.

Which of the following is/are semiconductors?

1. B

2. Al

3. Ga

4. Si

Q.

In which of the following elements +1 oxidation state is more stable than +3 oxidation state

1. Tl

2. Al

3. Ga

4. In

Q. Which one of the following pairs of chemical species contains the ions having same hybridisation of the central atoms?(1) NO2- and NH2-(2) NO2- andNO3- (3) NH4+ and NO3-(4) SCN- and NH2

Q.

Soft heavy metal melts at 30${}^{\circ }$ C and is used in making heat sensitive thermometers the metal is

1. Galium

2. Sodium

3. Potassium

4. Caesium

Q.

The order in which the atomic radius increases is as follows

1. 
2. 
3. 
4. 

Q. The element which exists as liquid upto ${2000}^{\circ }C\&$ can be used in high temperature thermometry is

1. B

2. Al

3. Ga

4. In

Q. In a close packing of atoms A of radius _{ra , }the radius of atom Bthat can be fitted in the tetrahedral void is (1)0.{225}_{ra } (2)0.{115}_{ra} (3)0.{414}_{ra} (4)0.{732}_r

Q. how to find eqivalent mass of O_{

Q.

The order in which the atomic radius increases is as follows

1. $Li>Be>B$
2. $Li<Be<B$
3. $Li>B<Be$
4. $Li<B>Be$

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

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Q.

The order in which the atomic radius increases is as follows

1. $Li>Be>B$
2. $Li<Be<B$
3. $Li>B<Be$
4. $Li<B>Be$

Q. 27. Is this true that only organic compounds have intramolecular H-bonds ?

Q. $B^{3+}$ ion cannot exist in an aqueous medium because of its:

1. Strong reducing property
2. Strong oxidising property
3. Small size and large charge
4. Large size and small charge

Q. $B^{3+}$ ion cannot exist in an aqueous medium because of its:

1. Strong reducing property
2. Strong oxidising property
3. Small size and large charge
4. Large size and small charge

Q. 14. In which of the following species the bond is non-directional?(a) NCl (b) RbCl (c) BeCl (d) BCl

Q.

The electronegativity of following elements increases in the order of?

1. N, Si, C, P

2. Si, P, C, N

3. P, Si, N, C

4. C, N, Si, P

Q.

In which of the following elements +1 oxidation state is more stable than +3 oxidation state?

1. Tl

2. Ga

3. Al

4. In