Chemistry PGT Mock Test 2026 – Online Practice Questions

Correct Answer: (c) AlN + CO

Explanation: Alumina reacts with carbon in the presence of nitrogen at high temperature to form aluminium nitride and carbon monoxide:

Al₂O₃ + 3C + N₂ → 2AlN + 3CO.

Explanation: Dimethylcyclohexane can exist in different positional and cis-trans configurations. Considering the possible positions of the two methyl groups and their stereochemical arrangements, a total of seven stereochemical isomers are possible.

Explanation: The compound consists of two rings having two carbon atoms in common. The total number of carbon atoms is four, represented by the suffix “butane”. Therefore, its IUPAC name is bicyclo(1,1,0)butane.

Explanation: According to the first law of thermodynamics, ΔU = Q − W. At constant volume, ΔV = 0, so pressure–volume work (W = PΔV) is zero. Therefore, the heat supplied at constant volume is equal to the change in internal energy:

qᵥ = ΔU

Thus, the correct answer is ΔU.

Exp. (1) Since XeF₄ and [Ni(CN)₄]²⁻ has square plane structure, so they are iso-structural.

Exp. (2) In cyclohexane, chair conformation is most stable and it is free from angle strain and torsional strain but boat conformation have some torsional strain.

Exp. (3) Friedel-Craft reaction usually fail for pyridine because catalysts used in this reaction are AlCl₃ or FeCl₃ coordinate with nitrogen to the pyridine through lone pair of electrons and form a complex compound. The positive (+ve) charge on 'N' greatly diminishes the reactivity towards electrophilic substitution.

Exp. (1)
Xsolute = 1 − (P° − Ps)/P°
= 1 − (40 − 20)/40
= 1 − 1/2
= 0.5

Explanation: Orthophosphoric acid has the chemical formula H₃PO₄. Basicity of an acid is the number of hydrogen ions (H⁺) that can be produced by the ionization of one molecule of the acid in aqueous solution. H₃PO₄ contains three ionizable hydrogen atoms, so its basicity is 3.

Exp. (2) Bragg's law provides the condition for a plane wave to be diffracted by a family of lattice planes
2d sin θ = nλ
Where, λ is wavelength
d is interplanar spacing
If dₕₖₗ is smaller than λ/2, there will be no Bragg-reflection of X-rays from a crystal.

Exp. (3) The explanation box shows:
A = C₆H₁₁–CH(Br)–CH₃
B = C₆H₁₁–CH₂–CH₂Br

Exp. (3) Given:

NH₄HS(s) ⇌ NH₃(g) + H₂S(g)

At equilibrium, pressure = 6 atm

∴ P₍NH₃₎ = P₍H₂S₎ = 3 atm

∴ Kₚ = P₍NH₃₎ × P₍H₂S₎

= 3 × 3 = 9 atm²

Exp. (2) Diatomic molecules like N₂, H₂, O₂ are infrared (IR) inactive because they do not have change in permanent dipole moment but they are Raman active because they show change in polarizability.

Explanation: In 1962, Neil Bartlett prepared O₂PtF₆ by reacting oxygen with the powerful oxidizing agent platinum hexafluoride (PtF₆). Since the ionization potential of xenon is close to that of oxygen, Bartlett replaced oxygen with xenon and obtained XePtF₆. This was the first true compound of a noble gas.

Explanation: In CH₃Li, the C–Li bond has predominantly ionic character. In (CH₃)₂Be, (CH₃)₃Al and (CH₃)₄Sn, the metal–carbon bonds are predominantly covalent. Therefore, CH₃Li differs from the other three in bonding.

Exp. (2) Certain aromatic aldehydes lose carbon monoxide when heated with aluminium chloride and benzene. The reaction products include the aromatic residue corresponding to the aldehyde, anthracene and triphenylcarbinol.

Exp. (1) Since both N₂⁺ and B₂ have unpaired electrons ω. So each electron having a magnetic moment, So both show paramagnetic character.

Explanation: The stability of a carbonium ion increases with an increase in the number of alkyl groups attached to the positively charged carbon atom. Alkyl groups stabilize the positive charge through their electron-releasing effect. Hence, the carbonium ion represented by option (b) is the most stable among the given structures.

Explanation: Benzyl chloride reacts with urotropine and on reflux gives benzaldehyde. This reaction is known as Sommelet's reaction.

Explanation: Dipole moment arises due to separation of charge in a molecule. It is influenced by differences in electronegativity and the distribution of electron density. Among the given compounds, the source identifies tert-butylbenzene, C₆H₅C(CH₃)₃, as having the maximum dipole moment.

Explanation: Carbon cannot expand its valence shell because of the non-availability of a 2d subshell. Therefore, carbon cannot accommodate six chlorine atoms around it to form [CCl₆]²⁻. Hence, [CCl₆]²⁻ cannot exist.

Exp. (2) Metallic sulphides like As₂S₃, Sb₂S₃ solutions are negatively charged colloids. So, effective ions for coagulation power will be cation.
According to Hardy-Shulze Rule, greater the valency of ion, greater will be coagulating power.
Highest coagulating power = Al³⁺

Explanation: The heat of neutralization of a strong acid with a strong base is highest because both are completely ionized in aqueous solution. NaOH and HCl are strong base and strong acid, respectively. Therefore, their reaction produces the maximum heat of neutralization.

Explanation: Ti (Z = 22) is a d-block element, whereas Te (Z = 52) is a p-block element. Si and S belong to the p-block, Li and Ba belong to the s-block, and La and Lu are placed in the f-block in the given classification. Therefore, Ti and Te do not belong to the same periodic block.

Exp. (4) From option (4)

K₂SO₄ → 2K⁺ + SO₄²⁻, n = 3

Cd(NO₃)₂ → Cd²⁺ + 2NO₃⁻, n = 3

From the above reaction 0.1 M K₂SO₄ and 0.1 M Cd(NO₃)₂ solutions are isotonic in nature because they give same number of solute particles in solution.

Exp. (2) Given,
λₘ = 412 S cm² mol⁻¹
Transport number:
t₊ = λ₊/(λ₊ + λ₋)
0.825 = λ₊/412
∴ λ₊ = 339.9
∴ Molar ionic concentration of Cl⁻ = λₘ − λ₊
= 412 − 339.9
= 72.1 S cm² mol⁻¹