Chemistry Test - 9

Internal energy is a quantity that represents the total energy of the system.

P, Q & R are true and S is false

• According to Baeyer's theory, cyclohexane is less stable than cyclopentane. However, cyclohexane and other higher cycloalkanes are found to be more stable than cyclopentane. The theory gives a planar model of cycloalkanes. The carbon-carbon double bond is easily formed.Baeyer's theory does not apply to four-membered rings.So, P is true.
• Cyclohexane has a non-polar structure that makes it almost free from ring strain.It exists as a puckered ring which is non-planar and the bond angles are close to tetrahedral bond angles.cyclodecane rings are not flat but are puckered.So, Q is true.
• The cyclohexane ring can assume many different shapes. A single cyclohexane molecule is in a continuous state of flexing or flipping into different shapes or conformations.Half chair form has some angle strain and some torsional strain but boat form has no significant angle strain and has the torsional strain. In this form hydrogen atoms are attached with the Van Der Waals forces. This interaction is known as flagpole interactions. So, R is true.

By adding electrolytes the colloidal particles are precipitated. The electrolytes neutralise the charge of colloids leading to their coagulation and thus destroy the colloid.

Methods used for the destruction of colloids are as follows:

1. Electrophoresis
2. Mixing two oppositely charged sols
3. Boiling
4. Persistent dialysis
5. By adding electrolyte

All the elements of the group 15 elements form tri oxides and pentoxides having the general formula M₂O₃ or M₂O₅.

The oxides of Nitrogen, Phosphorus, and Arsenic are acidic.

The trioxide of antimony Sb₂O₃ is amphoteric while that of bismuth Bi₂O₃ is basic.

As₂O₃ is acidic in nature.

The pentoxides of all these elements are acidic but acidic character decreases down the group.

Thus, P₂O₅ is the strongest acidic oxide whereas Bi₂O₃ is the weakest acidic oxide.

The acidic character of the same element increases with an increase in the oxidation state.

Thus, the most acidic oxide among the following is P₂O₅.

The general electronic configuration of alkaline earth metals is ns², which shows that these metals do not have any unpaired electrons. So, these metals show diamagnetic properties.

Vinyl Chloride,Butadiene,Styrene does not undergo additional polymerization.

In addition polymerization (sometimes called chain-growth polymerization), a chain reaction adds new monomer units to the growing polymer molecule one at a time through double or triple bonds in the monomer. In addition polymerization the growth of the polymer chain proceeds exclusively by reaction(s) between monomer(s) and reactive site(s) on the polymer chain.

Fluorine acts as a stronger oxidizing agent than oxygen because it is more electronegative than oxygen. So, it can easily attract electrons and get reduced. Thus, oxygen is a strong reducing agent than fluorine.

Therefore, both the Assertion and Reason are correct and Reason is the correct, explanation for Assertion.

The troposphere is the lowest layer of the atmosphere. It extends 10 km above sea level. The outer surface of the troposphere is the tropopause. In this layer, temperature decreases with increasing altitude. Aviation-related activities take place in the troposphere.

\(Ka =10^{-5} pH =6\)

\(pH=-logKa+log. \frac{[Salt]} {[Acid]}\), \(6=-\log 10^{-5}+\) \(log.\frac{[Salt]}{[Acid]}\)

\(6=5 \log 10+\) \(log.\frac{[Salt]}{[Acid]}\) \( 6=5+\) \(log.\frac{[Salt]}{[Acid]}\)

\(log.\frac{[Salt]}{[Acid]}\) \(=6=5=1,\) \(\frac{[Salt]}{[Acid]}=\frac{10}{1}\)

Since silane is most easily hydrolysed and forms metasilicate after removing \(H\). Thus, \(S i H_{4}\) is least stable to hydrolysis.

\(SiH _{4}+3 H _{2} O \longrightarrow H _{2} SiO _{3}+4 H _{2}\)