Chemistry: CUET Mock Test - 9 - CUET MCQ

Coagulation or precipitation is a process of aggregating together the colloidal particles to change them into large-sized particles which ultimately settle as a precipitate. The different methods to test the type of emulsion are-microscopic, conductance and dye method.

When ethylamine reacts with one mole of hydrochloric acid (HCl), the ammonium salt formed is ethylammonium chloride, which has the chemical formula C₂H₅NH₃⁺Cl^-
The reaction between ethylamine and HCl can be represented as follows:

CH₃CH₂ - NH₂ + HCl →

In this reaction, the HCl protonates the ethylamine to form ethylammonium ion (C2H5NH3+) and chloride ion (Cl-), which combine to form the ethylammonium chloride salt.
Ethylammonium chloride salt is formed when ethylamine reacts with one mole of HCl.

Based on inductive effect, solvation effect, and steric hindrance of the alkyl group in aqueous medium the basic strength order of the amines is:
(C2H5)2NH > (C2H5)3N > C2H5NH₂ > NH3

More is the substitution in amine, more is +I effect hence more will be the basic strength. The correct order of basic strength: 3° > 2° > 1°
In the gas phase, where intermolecular forces such as hydrogen bonding do not play a significant role, the basicity of amines is primarily determined by the availability of the lone pair of electrons on the nitrogen atom for bonding with a proton (H+), and by the effect of alkyl groups that can donate electron density to the nitrogen atom, increasing its basicity.
Primary (1°) amines have one alkyl group attached to the nitrogen atom, secondary (2°) amines have two, and tertiary (3°) amines have three. Alkyl groups are electron-donating groups that increase the electron density on the nitrogen atom, making it more basic by enhancing its ability to donate the lone pair of electrons.
Therefore, in the gas phase, without the effects of solvation (like hydrogen bonding in a solvent), the order of basicity is determined by the inductive effect of the alkyl groups. More alkyl groups means a stronger inductive effect, which increases the basicity. The correct order of basicity in the gas phase is:
3° > 2° > 1°

The pKb value indicates the basicity of a substance in water: higher pKb values correspond to weaker bases. Among the given amines:

• C2H5NH2 (ethylamine) is a primary aliphatic amine with a strong electron-donating ethyl group, making it relatively basic.
• C6H5NHCH3 (N-methylaniline) is a secondary amine with a phenyl group that reduces basicity via resonance.
• (C2H5)2NH (diethylamine) is a secondary aliphatic amine, highly basic due to two electron-donating ethyl groups.
• C6H5NH2 (aniline) is the least basic because the nitrogen’s lone pair is delocalized into the aromatic ring, reducing its availability for protonation.
  Thus, aniline (C6H5NH2) has the highest pKb value (D).

The Kb value indicates the basicity of an amine in aqueous solution: higher Kb values correspond to stronger bases. In aqueous solution, the basicity of amines depends on inductive effects, solvation, and steric hindrance. Diethylamine (C₂H₅)₂NH , a secondary amine, is the most basic due to the electron-donating effect of two ethyl groups and favorable solvation of its conjugate acid. The approximate order of basicity is:
(C₂H₅)₂NH > C₂H₅NH₂ > CH₃NH₂ > C₆H₅N(CH₃)₂
Thus, (C₂H₅)₂NH has the highest Kb value (C).

The passage describes boiling point elevation, a colligative property where the boiling point of a solvent (water) increases upon adding a non-volatile solute (NaCl). This is evident from the equation ΔT_b = K_b × m, where ΔT_b represents the change in boiling point. Other colligative properties, such as freezing point depression, vapor pressure lowering, and osmotic pressure, are not discussed in the passage. Thus, the correct answer is B.

The passage states that the increase in boiling point (ΔT_b) is proportional to the concentration of solute particles. The equation ΔT_b = K_b × m shows that ΔT_b is directly proportional to molality (m), the concentration of solute particles in moles per kilogram of solvent. Thus, the relationship is directly proportional (A).

The equation includes 'm,' which refers to molality (mol of solute/kg of solvent).

The passage explains that adding a non-volatile solute like NaCl increases the boiling point of water, as described by the colligative property of boiling point elevation. This occurs because NaCl reduces the vapor pressure of the solvent, requiring a higher temperature to reach the boiling point. Option D refers to freezing point depression, another colligative property, but is irrelevant here. Thus, the correct answer is C.

A non-volatile solute like NaCl does not evaporate easily because it has a high boiling point and does not contribute to the vapor pressure of the solution. This property causes boiling point elevation in the solvent (water). Option B is incorrect because NaCl is a solid, not a gas. Option C is incorrect because NaCl dissociates into Na+ and Cl- ions in water. Option D is incorrect because NaCl does not react with water to form a gas. Thus, the correct answer is A.

The reaction involves the formation of carbocation as intermediate. Hence more the stability of the carbocation, more will be the rate of reaction. Let us draw the structure of the corresponding carbocation and observe the relative stability of the four benzyl carbocations. The relative stability of the four carbocations is

Phenol is most acidic because its conjugate base is stabilised due to resonance, while the rest three compounds are alcohols, hence, their corrosponding conjugate bases do not exhibit resonance.

Such questions can be solved by considering the relative basic character of their conjugated bases which for H₂O, C₂H₂, H₂CO₃, and C₆H₅OH are:

-OH, HC ≡ C⁻, HCO₃⁻, C₆H₅O⁻

More the possibility for the dispersal of the negative charge, weaker will be the base. Thus the relative basic character of the four bases is:

HCO₃⁻ < C₆H₅O⁻ < -OH < HC ≡ C⁻

Due to resonance, the acidic character of the four corresponding acids will be:

H₂CO₃ > C₆H₅OH > H₂O > HC ≡ CH

Nitro group is strongly electron withdrawing group. At ortho position intra-molecular hydrogen bond reduces the acidic strength.

Oxo process involves formulation of alkene to form aldehyde only not ketone

Myoglobin or Haemoglobin

α-Amino acids