Chemistry Shaalaa.com Model Set 2 2020-2021 HSC Science (General) 12th Standard Board Exam Question Paper Solution

Dacron is a copolymer of ethylene glycol and _______________

adipic acid

hexamethylenediamine

phthalic acid

terephthalic acid

In which of the following structure of DNA carries genetic information of the organism?

the primary structure of DNA

the double helix structure of DNA

complementary base pairing

sugar-phosphate backbone

The rate law relates to the rate of a chemical reaction in terms of _______.

concentration of catalyst

temperature

potential energy

mol/L of reactants

The following will react faster by S_N1 mechanism

1-chloropropane

2-chloropropane

2-chloro-2-methylpropane

chloroethane

The change in internal energy in a reaction when 2kJ of heat is released by the system and 6 kJ of work is done on the system will be ______.

+4 kJ

4kJ

+3 kJ

– 8 kJ

In interhalogen compounds, which of the following halogens is never the central atom?

I

Cl

Br

F

The catalyst used for decomposition of KClO₃ is _______.

ZnO

MnO₂

CuO

K₂O

The following ion has the maximum number of unpaired electrons.

Sc³⁺

Ti³⁺

Fe³⁺

Co²⁺

The molar conductivity and conductivity of AgNO₃ solution is 121.4 Ω^–1 cm² mol^–1 and 2.428 × 10^–3 Ω^–1 cm^–1 at 25 °C. What is molar concentration of AgNO₃ solution?

0.2 M

0.02 M

2.0 M

2.2 M

For a reaction \[\ce{HCl_{(aq)} + H2O_{(l)} ⇌ H3O^+_{ (aq)} + Cl^-_{ (aq)}}\]

Which of the following is a conjugate acid-base pair?

HCl and H₂O

H₃O⁺

H₃O⁺ and H₂O

HCl and H₃O⁺

Which principle of green chemistry has its perspective towards carrying out reactions at room temperature and pressure?

Write the name of the catalyst used for preparation of high density polythene polymer.

Write the order of reactivity of alkyl halides with ammonia.

Give SI unit of resistivity.

Give SI unit of resistivity.

What is Lanthanoid contraction?

Write the name of the product when ketones react with 1,2-diol in presence of dry HCl.

Complete the following reaction.

\[\ce{H2N - CH2 - COOH + H2N - CH2 - CH2 - COOH ->[-H2O] ?}\]

Write industrial application of enzyme catalysis.

For a very dilute solution, the osmotic pressure is given by π = n₂RT/V where V is the volume in L containing n₂ moles of nonvolatile solute. Establish the equation for molar mass of solute.

Define molar solubility. Write it’s unit.

Distinguish between Order and Molecularity of reaction.

What is the action of following reagents on pent-3-enal?

1. H₂/Ni
2. LiAlH₄/H₃O⁺

How many moles of electrons are required for reduction of 2 moles of Zn²⁺ to Zn?

Explain. Aryl halides are less reactive than alkyl halides towards nucleophilic substitution reactions.

Write four points of distinction between Lanthanoids and Actinoids.

Write a classification of aliphatic ketones with a suitable example.

Describe the following:

Cannizzaro reaction

write the structure of the monomer used in natural rubber.

Calculate the number of unit cells in 0.3 g of a species having density of 8.5 g/cm³ and unit cell edge length 3.25 × 10^-8 cm.

Explain any three characteristic features of nanoparticles.

Explain Hoffmann’s exhaustive alkylation with suitable reactions.

Define buffer solution.

Explain the types of buffer solutions.

Why is molecularity applicable for only elementary reactions whereas order of a reaction is applicable for elementary and complex reactions? Explain with suitable examples.

State Kohlrausch law of independent migration of ions.

Define coordination number.

Define Anionic sphere complex.

Draw optical isomers of [Co(en)₃]³⁺.

What is Grignard reagent? How is it prepared? Why are they prepared under anhydrous condition?

Derive the expression for work done in chemical reaction. Write the relationship between ∆H and ∆U for an isochoric process.

Write three uses of sulfuric acid.

Discuss the position of d-block elements, lanthanoids and actinoids in the periodic table.

Discuss the position of d-block elements, lanthanoids and actinoids in the periodic table.

The unit cell of Na is bcc and its density is 0.97 g/cm³. What is the radius of a sodium atom if the molar mass of Na is 23 g/mol?

Explain the fact that in alkyl aryl ethers, the alkoxy group is ring activating and ortho/para directing towards electrophilic aromatic substitution.

An organic compound gives hydrogen on reaction with sodium metal. It forms an aldehyde with molecular formula C₂H₄O on oxidation with pyridinium chlorochromate. Give the chemical equations in support of these observations.

Calculate the standard enthalpy of formation of liquid methanol from the following data:

1. \[\ce{CH3OH_{(l)} + \frac{3}{2} O_{2(g)} -> CO_{2(g)} + 2H2O_{(l)}}\]     ∆H° = – 726 kJ mol^–1
2. \[\ce{C_{(Graphite)} + O_{2(g)} -> CO_{2(g)}}\]          ∆_cH° = – 393 kJ mol^–1
3. \[\ce{H_{2(g)} + \frac{1}{2} O_{2(g)} -> H2O_{(l)}}\]          ∆_fH° = – 286 kJ mol^–1 

Describe the manufacturing of H₂SO₄ by the contact process.

Explain, why [Co(NH₃)₆]³⁺ ion is low spin? Calculate number of unpaired electrons and write the geometry of [Co(NH₃)₆]³⁺.

Explain with vapour pressure-temperature curves that the freezing point of a solvent is lowered by dissolving a nonvolatile solute into it. Give reason for such lowering of freezing of solvent.