Chemistry Official 2024-2025 HSC Science (General) 12th Standard Board Exam Question Paper Solution

Schottky defect is NOT observed in ______.

NaCl

KCl

AgBr

NiO

The freezing point of 0.1 m aqueous solution of urea, if K_f for water is 1.86 K kg mol^-1 is ______.

1.86 °C

−1.86 °C

0.186 °C

−0.186 °C

Ozone layer is depleted by ______.

NO

NO₂

NO₃

N₂O₅

When an excess of AgNO₃ is added to the complex, one mole of AgCl is precipitated. The formula of the complex is ______.

[CoCl₂(NH₃)₄]Cl

[CoCl(NH₃)₄]Cl₂

[CoCl₃(NH₃)₃]

[Co(NH₃)₆]Cl₃

[CoCl(NH₃)₅]Cl₂

The value of Δn_g for the oxidation of 4 moles of sulphur dioxide to sulphur trioxide is ______.

−2

2

−4

4

One dimensional nanostructure amongst the following is:

Nanoparticles

Nanotubes

Nanofilms

Nanorods

Which formula co-relates degree of dissociation and concentration of electrolyte?

`c = sqrt ((K_a)/α)`

`α = sqrt ((K_a)/c)`

`c = sqrt( K_a  α)`

`c = sqrt (α/K _a)`

The highest acidic compound among the following is:

The formula used to calculate the molar conductivity of an electrolyte is ______.

`∧ = (1000c)/k`

`c = (1000∧)/k`

`∧ = (1000k)/c`

`k = 1000/(∧c)`

Which of the following is a secondary amine?

Cyclohexylamine

Isopropylamine

Diphenylamine

N, N-Dimethylaniline

Write the structural formula of N, N-dimethylethanamine.

Write the reagents used for the reduction of the carbonyl group in the Clemmensen reduction.

Write the IUPAC name of isoprene.

The rate law equation for \[\ce{A -> Product}\], is rate = k[A]^x. What is the effect of an increase in concentration of ‘A’ on the rate of reaction if x < 0?

What is the molality of an aqueous solution of KBr having freezing point −3.72°C (K_f for water is 1.86 K kg mol⁻¹)?

Write balanced chemical equation for the following:

When excess of ammonia is treated with chlorine.

Write the number of donor atoms present in EDTA during the formation of the complex.

Write the names of the metal elements in the brass alloy.

Derive an expression for the relation between half-life and rate constant for first-order reaction.

State Henry's law.

Define osmotic pressure.

Distinguish between lanthanoid and actinoids.

Write anomalous behaviour of oxygen with respect to atomicity.

Write anomalous behaviour of oxygen with respect to the oxidation state.

Write anomalous behaviour of oxygen with respect to magnetic property.

Write anomalous behaviour of oxygen with respect to the nature of hydrides.

What is the action of liquid bromine in acetic acid on anisole?

What is the action of soda-lime on sodium acetate?

Calculate the work done in kJ in a reaction if the volume of the reactant decreases from 8 dm³ to 4 dm³ against 43 bar pressure.

[1 dm³ bar = 100 J]

Explain ionization isomers with suitable example in complexes.

Explain the preparation of glucose from sucrose.

How many coulombs of electricity is required to produce 1g of sodium metal by reduction of sodium ion? 

Write the structural formula and IUPAC name of the alcohol having molecular formula C₄H₁₀O which does not undergo oxidation under normal condition.

Identify ‘A’ and ‘B’ in the following reaction and rewrite the complete reaction:

\[\ce{CH3 - CH = CH2 ->[HBr][Peroxide] A ->[alcoholic KCN][KBr] B}\]

Write the reaction for the preparation of acetaldehyde by Rosenmund reaction.

Write the general electronic configuration of 3d series.

Draw the structure of the following:

H₂SO₄

Write the molecular and structural formulae of thiosulfuric acid.

Define conjugate acid-base pair.

The hydroxyl ion concentration in an aqueous solution of NaOH is 2 × 10⁻⁴ mol dm⁻³. Calculate PH of the solution.

What is atom economy?

Explain any two applications of nanomaterials.

Define peptide bond.

How are peptide bonds formed?

Write the name and formula of the reagent used to convert alkylhalide to nitroalkane.

Write the reactions for the action of the following reagent on phenol:

Nitrating mixture

Write the reaction for the action of the following reagent on phenol: 

Zinc dust

What is the action of phosphorous pentacholoride on ethyl methyl ether?

Write the formula to calculate EAN.

Explain the formation of [CO(NH₃)₆]³⁺ complex ions with respect to the type of hybridisation.

Explain the formation of [CO(NH₃)₆]³⁺ complex ions with respect to magnetic property.

Calculate spin only magnetic moment of M²⁺ ion.
[atomic number of M = 26]

Write the condensed electronic configuration of Gadolinium [Z = 64].

Name different zones in the blast furnace. Write the reactions taking place in them.

Write the chemical equation involved in the carbylamine reaction for ethylamine.

Write the chemical equation involved in the following reaction:

Hoffmann-bromamide degradation reaction

Explain Cannizzaro's reaction with the help of benzaldehyde.

Write the reaction for the conversion of cyclohexene to adipic acid.

Define “zero order reaction”.

A reaction takes place in two steps:

1. \[\ce{NO_{(g)} + Cl2_{(g)} -> NOCl2_{(g)}}\]
2. \[\ce{NOCl2_{(g)} + NO_{(g)} -> 2NOCl_{(g)}}\]

1. Write the overall reaction.
2. Identify the reaction intermediate.
3. What is the molecularity of each step?

ΔH for the formation of ethane gas is −84.4 kJ at 300 K. Calculate ΔU for the reaction.

Mention the types of polymers formed on the basis of intermolecular forces.

Write any two uses of low density polyethylene.

An element with molar mass 27 g/mol forms a cubic unit cell with edge length of 405 pm. If the density of the element is 2.7 g/cm³, what is the nature of the cubic unit cell?

Derive the equation of Raoult’s law for binary solution containing non-volatile solute.

State whether entropy change is positive or negative in the following example:

Melting of ice

State whether entropy change is positive or negative in the following example: 

Vaporisation of a liquid

Explain the common ion effect with an example.

Draw a neat labelled diagram of a lead accumulator.

Write the overall reactions taking place at the cathode in a lead accumulator cell during discharging of the cell.

Write the overall reactions taking place at the anode in a lead accumulator cell during discharging of the cell.

Define unit cell.

Which colour is shown by NaCl crystal due to formation of F-centre?

Why does fluorine show anomalous behaviour in ‘17 group’ elements?

Write salient features of S_N2 mechanism.

What is the action of the following reagent on bromomethane?

bromobenzene

What is the action of the following reagents on bromomethane?

Mercurous fluoride