chemistry MCQs - 12th class Chapter 03 Mcqs

1

Which element is described as non-metallic in Group IIIA?

A

Aluminium

B

Gallium

C

Boron

D

Indium

2

What is the chemical formula for Borax or Tincal?

A

Ca₂B₆O₁₁.5H₂O

B

H₃BO₃

C

Na₂B₄O₇.10H₂O

D

Al₂O₃

3

Aluminium is the ____ most abundant element in the earth's crust.

A

first

B

second

C

third

D

fourth

4

Which mineral of aluminium has the chemical formula Na₃AlF₆?

A

Bauxite

B

Corundum

C

Gibbsite

D

Cryolite

5

What are the common oxidation states of Boron?

A

+1 and -1

B

+2 and -2

C

+3 and -3

D

+4 and -4

6

Borax is the sodium salt of which acid?

A

Boric acid

B

Orthoboric acid

C

Metaboric acid

D

Tetraboric acid

7

In the manufacture of borax from colemanite, what substance is precipitated out?

A

NaBO₂

B

CaCO₃

C

Na₂CO₃

D

Ca(OH)₂

8

An aqueous solution of borax is alkaline in nature due to ____.

A

ionization

B

dissociation

C

hydrolysis

D

neutralization

9

What is the colour of a borax bead with cupric oxide in the oxidizing flame?

A

Green

B

Red

C

Blue

D

Yellow

10

Which of the following is NOT a use of borax?

A

Softening of water

B

As a flux in welding

C

Making washing powders

D

As a primary fuel source

11

Which of the following is the most stable boric acid?

A

Metaboric Acid

B

Tetraboric Acid

C

Pyroboric Acid

D

Orthoboric Acid

12

When orthoboric acid (H₃BO₃) is heated to 100°C, it converts into ____.

A

Boric anhydride

B

Metaboric Acid (HBO₂)

C

Tetraboric acid

D

Borax

13

In the presence of which substance can boric acid be titrated against a standard alkali?

A

Glycerol

B

Ethanol

C

Methanol

D

Water

14

When aluminium powder is heated to 800°C in air, it forms aluminium oxide and ____.

A

Aluminium chloride

B

Aluminium hydride

C

Aluminium sulphide

D

Aluminium nitride (AlN)

15

Aluminium is amphoteric, meaning it dissolves in both ____.

A

water and oil

B

alcohols and ethers

C

acids and bases

D

salts and esters

16

Aluminium does not react with nitric acid due to the formation of a protective layer of ____.

A

aluminium nitride

B

aluminium hydroxide

C

aluminium oxide

D

aluminium sulphate

17

Which property of aluminium makes it useful for making cooking utensils and window frames?

A

It is magnetic

B

It is highly reactive

C

It is non-toxic

D

It is brittle

18

Which of the following elements in Group IVA is a metalloid?

A

Carbon

B

Silicon

C

Germanium

D

Lead

19

The property of forming long chains of identical atoms is called ____.

A

isomerism

B

allotropy

C

catenation

D

polymerization

20

The oxides of germanium, tin, and lead are ____ in nature.

A

acidic

B

basic

C

neutral

D

amphoteric

21

What is the chemical formula for dolomite, a mineral of carbon?

A

CaCO₃

B

MgCO₃

C

MgCO₃.CaCO₃

D

ZrSiO₄

22

What percentage of the Earth's crust mass is composed of silicon?

A

About 10%

B

About 25%

C

About 50%

D

About 75%

23

Which of the following is a crystalline form of silica?

A

Clay

B

Sand

C

Opal

D

Quartz

24

Carbon monoxide (CO) molecule has a ____ bond between the two atoms.

A

single

B

double

C

triple

D

ionic

25

What is the geometry of a carbon dioxide (CO₂) molecule?

A

Trigonal planar

B

Tetrahedral

C

Bent

D

Linear

26

Vitreous silica is resistant towards all acids except ____.

A

HCl

B

H₂SO₄

C

HNO₃

D

HF

27

In the silica network, every silicon atom is bonded tetrahedrally to how many oxygen atoms?

A

One

B

Two

C

Three

D

Four

28

Sodium silicate (Na₂SiO₃) is commonly known as ____.

A

caustic soda

B

washing soda

C

water glass

D

baking soda

29

The weathering of potassium feldspar results in the formation of potassium carbonate, sand, and ____.

A

clay

B

bauxite

C

limestone

D

gypsum

30

What is the common name for magnesium silicate, Mg₃H₂(SiO₃)₄?

A

Asbestos

B

Talc or Soapstone

C

Kaolin

D

Zircon

31

What compound is formed when SiCl₂(CH₃)₂ reacts with water?

A

Silane

B

Silicon carbide

C

A methyl silicone

D

Silicon dioxide

32

The most outstanding physical attribute of silicone oil is its ____.

A

high volatility

B

low boiling point

C

small change in viscosity with temperature

D

high reactivity

33

A substance that has different resistances to the passage of electric current under different circumstances is called a ____.

A

conductor

B

insulator

C

superconductor

D

semiconductor

34

When a semiconductor is heated, its resistance ____.

A

increases

B

decreases

C

remains the same

D

becomes zero

35

Which lead oxide is a black powder obtained by heating plumbous oxalate?

A

Lead monoxide (PbO)

B

Lead suboxide (Pb₂O)

C

Triplumbic tetraoxide (Pb₃O₄)

D

Lead dioxide (PbO₂)

36

What is the common name for Lead Monoxide (PbO)?

A

White lead

B

Red lead

C

Litharge

D

Chrome yellow

37

Triplumbic tetraoxide (Pb₃O₄) is also known as ____.

A

Minium or red lead

B

Massicot

C

White lead

D

Litharge

38

Basic lead carbonate, 2PbCO₃.Pb(OH)₂, is commonly known as ____.

A

Red lead

B

Chrome yellow

C

White lead

D

Lead chromate

39

White lead is not a suitable pigment because it is darkened by ____ in the atmosphere.

A

oxygen

B

carbon dioxide

C

nitrogen

D

hydrogen sulphide

40

The chemical formula for lead chromate is ____.

A

PbO

B

PbO₂

C

PbCrO₄

D

PbSO₄

41

Which element is essential in very small amounts for the proper growth of many plants?

A

Aluminium

B

Boron

C

Thallium

D

Gallium

42

What is the atomic number of Thallium (Tl)?

A

13

B

31

C

49

D

81

43

In the borax bead test, the coloured compounds formed are metallic ____.

A

borides

B

borates

C

nitrides

D

carbides

44

Boric acid is a ____ acid.

A

very strong

B

moderately strong

C

very weak

D

neutral

45

Aluminium foil is used to jam radar because it is an excellent reflector of ____.

A

sound waves

B

radiant energy

C

light waves

D

magnetic fields

46

The pair of valence electrons that do not readily take part in chemical combination is termed as ____.

A

lone pair

B

bond pair

C

inert pair

D

electron pair

47

Unlike carbon, silicon is not found in a free state and is a major constituent of ____.

A

atmosphere

B

living organisms

C

rocks

D

sea water

48

The simplest formula for silica is ____.

A

SiO

B

Si₂O

C

SiO₂

D

SiO₃

49

Asbestos, used for incombustible fabrics, is a hydrated silicate of calcium and ____.

A

sodium

B

magnesium

C

aluminium

D

iron

50

Silicones are used to make surfaces ____.

A

water absorbent

B

water repellent

C

conductive

D

brittle