Assertion: If aluminium atoms replace a few silicon atoms in three-dimensional network of silicon dioxide, the overall structure acquires a negative charge.

Reason: Aluminium is trivalent while silicon is tetravalent.

1. Both assertion and reason are true and the reason is the correct explanation of assertion.

2. Both assertion and reason are true and the reason is not the correct explanation of assertion.

3. Assertion is true but the reason is false.

4. Assertion is false but the reason is true.

Assertion: Silicones are water-repelling in nature.

Reason: Silicones are organosilicon polymers, which have $(-{\mathrm{R}}_2\mathrm{SiO}-)$ as repeating units.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true, but the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Match the species given in Column I with the hybridisation given in Column II.

Codes

          A          B          C           D       

1.      ii             iii         i             iii

2.     i            i           iii           ii

3.     iii            ii         ii            i

4.    i           iii            ii             iii

Match the species given in Column I with properties given in Column II.

Match the species given in Column I with the properties mentioned in Column II.

Codes

Which of the following statements are correct?

(Answer on the basis of the given figure.)

a. The two bridged hydrogen atoms and the two boron atoms lie in one plane

b.  Out of six B-H bonds, two bonds can be described in terms of 3-center-2-electron bonds

c.  Out of six B-H bonds, four B-H bonds can be described in terms of 3 center 2 electron bonds

d.  The four-terminal B-H bonds are two center-two electron angular bonds

Choose the correct option

1. (a, b, c)
2. (b, c, d)
3. (a, c, d)
4. (a, b, d)

The correct statements among the following are-

a. Fullerenes have dangling bonds

b. Fullerenes are cage-like molecules

c. Graphite is thermodynamically most stable allotrope of carbon

d. Graphite is slippery and hard and therefore used as a dry lubricant in machines.

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

Me₃SiCl is used during polymerization of organ silicones because

a.  Chain length of organic silicone polymers can be controlled by adding ${\mathrm{Me}}_3\mathrm{SiCl}$

b.  ${\mathrm{Me}}_3\mathrm{SiCl}$ blocks the end terminal of silicone polymer

c.  ${\mathrm{Me}}_3\mathrm{SiCl}$ improves the quality and yield of the polymer

4.  ${\mathrm{Me}}_3\mathrm{SiCl}$ acts as a catalyst during polymerization

Choose the correct option

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

The linear shape of CO₂ is due to _______.

a.  sp³ hybridisation of carbon

b.  sp hybridisation of carbon

c.  $\mathrm{p\pi }-\mathrm{p\pi }$ bonding between carbon and oxygen

d.  sp² hybridisation of carbon

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

The reason for the small radius of Ga compared to Al is-.

a.  Poor screening effect of d and f orbitals

b.  Increase in nuclear charge

c.  Presence of higher orbitals

d.  Higher atomic number

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)