Chemistry NCERT Exemplar Solutions Class 11th Chapter Eleven

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(A) & (B)

The atomic radii decrease as one moves down the group from Al to Ga due to the shielding effect of electrons. As a result of this ineffective effect, the effective nuclear charge rises.

This is a Multiple Choice Questions as classified in NCERT Exemplar

B

Cement is made by combining lime ( CaO ), clay with silica ( SiO), and oxides of aluminum, magnesium, and iron.

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C

Explanation:

Solid CO₂ is referred to as dry ice because it is used in laboratories to create an ice bath for organic reactions. It is made by rapidly cooling high-pressure CO₂ gas.

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D

Reducing agent are compound that donates electron to an electron recipient compound. Reducing agents oxidize themselves and reduce the other compounds. They easily lose electrons and increase their oxidation state; those electrons are accepted by electron needed compounds.

In SnCl₂, Sn is in +2 oxidation state and can easily lose its two electrons and oxidize to +4 stable oxidation state.

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B

Quartz is a crystalline form of silica that can be converted into other crystalline forms at high temperatures. It's commonly used as a piezoelectric material.

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B

The four terminal hydrogen atoms and two boron atoms are all in the same plane.

There are two bridging hydrogen atoms above and below this plane.

The four terminal B-H bonds are regular two-centre-two-electron bonds, whereas the two bridge (B-H-B) bonds are unique and can be described as three-centre-two-electron bonds, as shown in figure:

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C

Me₃SiCl is a soleuless liquid That has a major application in the formation of silicones. On its addition in the process, it blocks the end and controls the chain length of the polymer.

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B

In group 14, as we move down from C to Sn, the size increases and electronegativity decreases. This results in the decrease in M-M bond energy. Hence the catenation property decreases.

Bond energy is the amount of energy required to fragment the atoms combined in a molecule are born into separate atoms. Carbon has maximum bond energy as compared to its other group elements. Therefore, shows maximum catenation property.