Chemistry Set 1 2017-2018 HSC Science (General) 12th Standard Board Exam Question Paper Solution

What is the role of the following compound -
CaF₂ in metallurgy of aluminum?

What is the role of the following compound- 
SiO₂ in the extraction of copper from copper pyrites?

Classify the following molecular solids into different types: 

1. HCl
2. CO₂
3. Solid ice
4. SO₂

Define the following terms : 
a. Cryoscopic constant
b. Resistivity 

Arrange the following oxyacids of chlorine in decreasing order of their thermal stability. Give reason.
 HOClO, HOCl, HClO₄, HOClO₂

Derive van’t Hoff general solution equation 

Represent a cell consisting of Mg²⁺ | Mg half cell and Ag⁺
 | Ag half cell and write the cell reaction.
( `"E"_("Ag")^° = 0.799 "V", "E"_("Mg")^° = - 2.37 "V"`)

Define the order of the chemical reaction.

Find the overall order of the following reactions: 
1. CHCl_3(g) + Cl_2(g) → CCl_4(g) + HCl_(g), Rate = k[CHCl₃][Cl₂]
2. 2NO_(g) + O_2(g) → 2NO_2(g),  Rate = k[NO]²[O₂]

State and explain Hess’s law of constant heat summation.

Explain the following with the help of balanced chemical equation:
a. Bleaching action of SO₂.
b. Dehydration of formic acid by concentrated H₂SO₄.
c. Burning of benzene in presence of excess of dioxygen.

The density of silver having an atomic mass of 107.8 g mol^{- 1} is 10.8 g cm^-3. If the edge length of cubic unit cell is 4.05 × 10^{- 8}
 cm, find the number of silver atoms in the unit cell.
 ( N_A = 6.022 × 10²³, 1 Å = 10^-8 cm)

How much quantity of electricity in coulomb is required to deposit 1.346 × 10^-3 kg of Ag in 3.5 minutes from AgNO₃ solution?
( Given: Molar mass of Ag is 108 × 10^-3 kg mol^-1 )

5 moles of helium expand isothermally and reversibly from a pressure 40 × 10^-5  N m^-2 to 4 × 10^-5 N m^-2  at 300 K. Calculate the work done, change in internal energy and heat absorbed during the expansion. (R = 8.314 J K^-1  mol^-1).

Write structure and molecular formula for the following compounds:
a. Orthophosphoric acid 
b. Sulphurous acid

What is the ‘Ellingham diagram’? Write any ‘two points’ of its significance. 

In a first-order reaction A → product, 80% of the given sample of compound decomposes in 40 min. What is the half-life period of the reaction? 

Write features of a reversible process.

Write any ‘four points’ of difference between fluorine and other halogens.

What is the freezing point of a liquid? The freezing point of pure benzene is 278.4 K. Calculate the freezing point of the solution when 2.0 g of a solute having molecular weight 100 g mol^-1
 is added to 100 g of benzene.
( K_f of benzene = 5.12 K kg mol^-1 .) 

A substance which shows the highest entropy is ___________.

SrCO_3(s)

Cu_(s)

NaCl_(aq.)

Cl_2(g)

The process of extracting a soluble material from an insoluble solid by dissolving out in a suitable solvent is known as _________. 

calcination

roasting 

leaching 

smelting 

The kinetic order for the following reaction is ________. 
\[\ce{2N_2O_(g) ->[Pt] 2N_2_(g) + O_2_(g) }\]

zero 

first

second

third

Which of the following compounds of chlorine is used as refrigerant? 

CCl₃NO₂

CCl₂F₂

COCl₂

CCl₄

4.0 grams of NaOH ( Molar mass = 40.0 g mol^-1 ) is dissolved in 500 cm³ of water. What is the molarity of NaOH solution? 

1 M

0.8 M

0.5 M

0.2 M

Number of types of orthorhombic unit cell is ___________.

7

3

4

2

The S.I. unit of cell constant for conductivity cell is __________.

m^-1

S m^-2

cm^-2

S dm² mol^-1

Explain the geometry of [Cu(NH₃)₄]²⁺ on the basis of hybridisation [ At. No. Cu = 29 ]. 

What are 'd' and 'f' block elements?

Write a short note on Sandmeyer’s reaction. 

What is the action of the following on isopropyl methyl ether? 
a. Cold HI
b. Hot HI

Write balanced equation for the following conversion: 
a. Cyclopropane carboxylic acid to cyclopropylmethanol.
b. Acetyl chloride to benzyl methyl ketone using dialkyl cadmium. 

What is the action of lithium aluminum hydride in the presence of ether on the following compounds? 
a. Nitroethane 
b. 2-Methyl-1-nitropropane

How is glucose prepared from starch? 

Define:
a. Analgesics 
b. Antimicrobials 

Complete and rewrite the balanced chemical equation for the following reactions: 
a. \[\ce{1-chloro-2, 4-dinitrobenzene ->[aq. alkali][368 K, H+]}\] ?

b. \[\ce{Benzaldehyde ->[50‰ KOH] }\] ?

c. \[\ce{Acetone + phenylhydrazine ->[H+]}\] ?

Write a preparation of phenol from cumene? What happens when phenol is heated with zinc dust? 

What are racemates?

What is the action of following reagents on glucose?
1. Bromine water
2. Hydroxylamine

What are elastomers? 

Distinguish between thermoplastic polymers and thermosetting polymers.

What is the action of the following on lanthanoids?
a. water
b. Sulphur, heat
c. nitrogen, heat

Draw the structures of veronal and thymine. 

Identify A and B from the following reaction and rewrite complete reaction: 

Write the preparation of benzoic acid from the following: 
a. styrene
b. benzamide
c. dry ice

Write resonance structures of aniline. What is the action of benzene diazonium chloride on ethanol? 

Write the formula for pentaamminechlorocobalt (III) sulphate. 

A polymer which contains ester linkage is_______.

teflon

buna-N 

dextron

neoprene 

An antihistamine drug is _______.

salvarsan

chloramphenicol

seldane 

prontosil 

Identify A and B respectively in the following reaction:
\[\ce{tert-butyl alcohol ->[20‰H2SO4][363K] A + H2O ->[HBr][H2O2] B}\]

2 - Methylpropene, 1- bromo - 2 - methylpropane

2 - Methylpropene, 2 - bromo - 2 - methylpropane

2 - Methylpropane, 1 - bromo - 2 - methylpropane

2 - Methylpropane, 2 - bromo - 2 - methylpropane 

The ligand triethylenetetramine is _______.

monodentate 

bidentate

tridentate 

tetradentate 

Pyrolusite ore is _______.

MnO

MnO₂ 

Mn₂O₇

Mn₂O₃

\[\ce{C2H5 - Br + Nal ->[dry acetone] C2H5 - I + NaBr}\]
The above reaction is _______.

Wurtz reaction

Balz-Schiemann reaction

Swarts reaction 

Finkelstein reaction

The functional group present in triacylglycerol is _______.

alcohol

ether

ester

amine