ecat chemistry past papers Mcqs

1

Compounds in which carbon atoms form only single bonds with other atoms are called?

A

Unsaturated compounds

B

Aromatic compounds

C

Saturated compounds

D

Alkynes

2

Which family of hydrocarbons is the main subject of this chapter?

A

Alkenes

B

Alkynes

C

Aromatic hydrocarbons

D

Alkanes

3

What is the general formula for alkanes?

A

CnH2n

B

CnH2n-2

C

CnHn

D

CnH2n+2

4

In the IUPAC name for an organic compound, what does the 'root' part tell us?

A

The class of the compound

B

The number of carbon atoms in the longest chain

C

The groups attached to the chain

D

The type of bonding

5

The IUPAC root name 'Pent-' corresponds to how many carbon atoms?

A

4

B

5

C

6

D

7

6

What is the distinguishing feature of alkanes that makes them distinct from other compounds?

A

Their high reactivity

B

Their vibrant colors

C

Their lack of reactivity towards usual reagents

D

Their solubility in water

7

The reaction of alkanes with chlorine in the presence of sunlight is an example of what type of reaction?

A

Addition

B

Photochemical substitution

C

Combustion

D

Cracking

8

What catalyst is used in the cracking of naphtha to produce smaller hydrocarbons?

A

Nickel

B

Zinc

C

Zeolite

D

Iron

9

The process of converting alkenes and alkynes to alkanes using hydrogen gas is called?

A

Halogenation

B

Combustion

C

Cracking

D

Hydrogenation

10

Which metal is used as a catalyst for the hydrogenation of ethene to ethane?

A

Zinc

B

Sodium

C

Nickel

D

Magnesium

11

Alkanes are also referred to as paraffins, which means what?

A

High affinity

B

Very reactive

C

Little affinity

D

Light bearing

12

The unreactivity of alkanes is explained by the ______ of their C-C and C-H bonds.

A

polarity

B

ionic nature

C

non-polarity

D

metallic nature

13

Complete combustion of any alkane produces which two substances?

A

Carbon monoxide and water

B

Carbon and hydrogen

C

Carbon dioxide and water

D

Oxygen and carbon

14

What is the IUPAC name for the compound CH3-CH(CH3)-CH2-CH3?

A

Pentane

B

2-Methylbutane

C

3-Methylbutane

D

Dimethylpropane

15

The reduction of alkyl halides (R-X) to alkanes can be achieved using hydrogen generated by?

A

Ni and H2

B

Sunlight

C

Zeolite at 500°C

D

Zn and HCl

16

When methane reacts with excess chlorine, what is the final product?

A

Chloromethane

B

Dichloromethane

C

Trichloromethane

D

Tetrachloromethane

17

Which term describes a reaction where one atom or group of atoms is replaced by another?

A

Addition

B

Substitution

C

Elimination

D

Rearrangement

18

Hydrocarbons are organic compounds containing only which two elements?

A

Carbon and Oxygen

B

Hydrogen and Nitrogen

C

Carbon and Hydrogen

D

Carbon and Halogens

19

Which of the following is a use for methane mentioned in the text?

A

Making plastics

B

Making synthetic fibres

C

Making carbon black

D

Making perfumes

20

In the IUPAC system, the part of the name that tells us about the class of organic compounds is the?

A

Prefix

B

Root

C

Suffix

D

Locator

21

Which alkane cannot be prepared by the hydrogenation of alkenes or alkynes?

A

Ethane

B

Propane

C

Butane

D

Methane

22

A structural formula shows the symbols for atoms connected by short lines which represent?

A

Electrons

B

Nuclei

C

Bonds

D

Energy levels

23

The reaction CH4 + 2O2 -> CO2 + 2H2O is an example of?

A

Halogenation

B

Cracking

C

Combustion

D

Substitution

24

Which other atom is almost always present along with the carbon atom in all organic compounds?

A

Oxygen

B

Nitrogen

C

Hydrogen

D

Halogen

25

Which metal can be used to reduce alkyl halides according to the options in the book's exercise?

A

Al

B

Mg

C

Ni

D

Co

26

If naphtha undergoes a combustion reaction, what products do you expect to form?

A

Alkanes

B

Alkenes

C

CO2 and H2O

D

Both alkanes and alkenes

27

Why does a mixture of zinc and hydrochloric acid act as a reducing agent?

A

Because zinc acts as a reducing agent

B

Because atomic hydrogen is produced

C

Because molecular hydrogen is produced

D

Because chloride ions are produced

28

Which alkane will evolve the most amount of heat when it is burnt with oxygen?

A

Ethane

B

Propane

C

Butane

D

iso-Butane

29

Indicate the most reactive hydrocarbon from the given options.

A

CH3-CH3

B

CH2=CH2

C

CH≡CH

D

CH4

30

Which hydrocarbon is responsible for explosions in coal mines?

A

Butane

B

Pentane

C

Methane

D

Ethene

31

Which product will be formed when ethyl bromide (C2H5Br) is treated with Zn/HCl?

A

CH4

B

CH3-CH3

C

CH3-CH2-CH2-CH3

D

CH3-CH2-CH3

32

Which of the following is not a process of halogenation of alkanes?

A

Cracking

B

Chlorination

C

Bromination

D

Iodination

33

How many moles of oxygen will be required to completely burn propane?

A

4 moles

B

5 moles

C

3 moles

D

6 moles

34

Cracking of hydrocarbons is done at high temperature in the presence of a?

A

Acid

B

Base

C

Sunlight

D

Catalyst

35

The process of cracking helps to balance the supply and demand of which product?

A

Plastics

B

Medicines

C

Petroleum fractions

D

Synthetic fibres

36

What is the IUPAC root for a chain of 7 carbon atoms?

A

Hex-

B

Hept-

C

Oct-

D

Non-

37

The reaction of alkanes with halogens is carried out in the presence of?

A

High pressure

B

A metal catalyst

C

Sunlight

D

Water

38

Trichloromethane is also commonly known as?

A

Carbon tet

B

Freon

C

Chloroform

D

Dichloromethane

39

The bonding electrons in C-H and C-C bonds are almost equally shared, making alkanes?

A

Polar

B

Ionic

C

Reactive

D

Non-polar

40

What is the condensed formula for methane?

A

C2H6

B

CH4

C

C3H8

D

CH3OH

41

Ethyne is reduced to ethane in the presence of Nickel catalyst at what temperature?

A

100°C

B

200°C

C

300°C

D

500°C

42

What type of formula is H-C(H)(H)-C(H)(H)-H?

A

Molecular Formula

B

Condensed Formula

C

Structural Formula

D

Empirical Formula

43

Reduction of unsaturated compounds like alkenes is used to prepare?

A

Perfumes

B

Banaspati ghee and margarine

C

Plastics

D

Medicines

44

The electronegativity value of carbon is given as?

A

2.1

B

2.5

C

3.0

D

3.5

45

The electronegativity value of hydrogen is given as?

A

2.1

B

2.5

C

2.8

D

2.0

46

A mixture of natural gas (methane) and air can do what when ignited?

A

Implode

B

Liquefy

C

Explode

D

Solidify

47

In the IUPAC name 2-Methylbutane, 'methyl-' is the?

A

Root

B

Suffix

C

Prefix

D

Solvent

48

What is the primary reason scientists have agreed to adopt SI units?

A

They are traditional units

B

To make conversions difficult

C

They are standard and user-friendly

D

They are only used in Europe

49

SI units use a base number for easy conversion, just like our number system. What is that base number?

A

2

B

8

C

10

D

16

50

Which system of units is used almost everywhere in the world, allowing scientists to use a single standard for exchanging data?

A

CGS System

B

MKS System

C

Imperial System

D

SI System

51

Using SI units enables scientists to compare results, replicate experiments, and benefit from each other's work, which advances the frontiers of what?

A

Knowledge

B

Wealth

C

Culture

D

Politics

52

How many base units are there in the SI system for physical quantities?

A

Five

B

Six

C

Seven

D

Ten

53

Which of the following is the standard unit of length in the SI system?

A

Foot

B

Yard

C

Metre

D

Inch

54

The kilogram (kg) is the standard unit of what physical quantity?

A

Length

B

Time

C

Mass

D

Temperature

55

A kilogram is also defined as the mass of what volume of water?

A

100 cm³

B

500 cm³

C

1000 cm³

D

10 cm³

56

What is the standard unit of time in the SI system, symbolized by 's'?

A

Minute

B

Hour

C

Second

D

Day

57

The unit 'second' is based on the radiation cycles of which atom?

A

Helium-4

B

Carbon-12

C

Cesium-133

D

Uranium-235

58

What is the standard unit of temperature in the SI system, represented by K?

A

Celsius

B

Fahrenheit

C

Kelvin

D

Rankine

59

The Kelvin is defined as 1/273rd of the thermodynamic temperature of what?

A

The boiling point of water

B

The freezing point of water

C

The triple point of water

D

The critical point of water

60

What is the base unit for the amount of a pure substance, denoted by 'mol'?

A

Gram

B

Mole

C

Dozen

D

Particle

61

A mole is defined as having exactly how many particles of a substance?

A

6.022 x 10²⁰

B

3.141 x 10²³

C

6.022 x 10²³

D

1.602 x 10⁻¹⁹

62

Which of the following is a derived unit in the SI system?

A

Meter (m)

B

Kilogram (kg)

C

Second (s)

D

Cubic meter (m³)

63

What is the derived unit for density in the SI system?

A

kg per meter

B

kg per square meter

C

kg per cubic meter

D

g per cubic centimeter

64

The unit for force, Newton (N), is derived from which combination of base units?

A

kg·m·s⁻¹

B

kg·m·s⁻²

C

kg·m²·s⁻²

D

kg·m⁻¹·s⁻²

65

What does the SI prefix 'kilo' (k) represent?

A

10³

B

10⁶

C

10⁻³

D

10⁻²

66

Which SI prefix represents the fraction 10⁻³?

A

Deci

B

Centi

C

Milli

D

Micro

67

For what reason do chemists often measure the masses of reactants in grams?

A

It is the official SI unit for mass

B

Molar mass is expressed in grams per mole

C

Grams are larger than kilograms

D

It is less accurate

68

Why is the Celsius scale often used in chemistry instead of the Kelvin scale?

A

It is the official SI unit

B

It is more convenient and compatible with the base ten system

C

It has more divisions than Kelvin

D

It is harder to convert to Kelvin

69

What unit of volume is typically used in a chemistry lab for smaller quantities?

A

Cubic meter

B

Liter

C

Cubic centimeter

D

Gallon

70

The level of uncertainty that every measurement carries is known as what?

A

Error

B

Precision

C

Accuracy

D

Certainty

71

An error can occur due to the limitation of the measuring instrument or the skill of the person making the measurement?

A

True

B

False

C

Only due to instruments

D

Only due to skill

72

What type of error affects the accuracy of a measurement and can be removed by a constant adjustment?

A

Random error

B

Systematic error

C

Parallax error

D

Human error

73

A pipette or burette delivering a volume slightly different from its graduation is an example of what kind of error?

A

Random error

B

Procedural error

C

Systematic error

D

Observational error

74

What type of error comes from unpredictable changes during an experiment and causes one measurement to differ slightly from the next?

A

Systematic error

B

Constant error

C

Random error

D

Instrumental error

75

Reading a volume from a measuring cylinder from a different angle each time is an example of a?

A

Systematic error

B

Random error

C

Zero error

D

Calibration error

76

A random error often determines the what of the experiment?

A

Accuracy

B

Outcome

C

Precision

D

Hypothesis

77

What term measures how close results are to the true or known value?

A

Precision

B

Reliability

C

Reproducibility

D

Accuracy

78

The closeness of two or more measurements to each other is known as?

A

Accuracy

B

Precision

C

Correctness

D

Certainty

79

If you weigh a substance five times and get 3.2 kg each time, your measurement is considered what?

A

Accurate

B

Precise

C

Both accurate and precise

D

Neither accurate nor precise

80

Can a measurement be precise but not accurate?

A

Yes

B

No

C

Only in physics

D

Only with digital tools

81

A student measures an object with a true mass of 20g and gets readings of 19.8, 20.5, and 19.6. This student is considered more?

A

Precise but not accurate

B

Accurate but not precise

C

Both accurate and precise

D

Neither accurate nor precise

82

Which of the following pairs of quantities can be measured in the same unit?

A

Heat and temperature

B

Temperature and area

C

Heat and work

D

Length and work

83

What is the SI unit of pressure?

A

Newton per metre

B

Joule

C

Pascal

D

Newton per gram

84

The symbol for kilogram in SI units is?

A

K

B

Kgm

C

kg

D

kG

85

What does a mole (mol) represent?

A

Number of particles

B

Mass

C

Volume

D

Length

86

Which prefix is used for 10⁻⁹?

A

Nano

B

Micro

C

Pico

D

Giga

87

What does the prefix 'Mega' (M) stand for?

A

10³

B

10⁶

C

10⁹

D

10⁻⁶

88

The derived unit for area in the SI system is?

A

Square centimeter

B

Square meter

C

Hectare

D

Acre

89

Pressure is expressed in Pascals (Pa), which is equivalent to what?

A

N·m

B

N·m⁻¹

C

N·m⁻²

D

N·m²

90

The unit for energy, Joule (J), is equivalent to?

A

N·m⁻¹

B

N·m

C

Pa·m³

D

kg·m·s⁻¹

91

Which error may occur due to limitations of instruments, environmental factors, and slight variations in procedure?

A

Systematic error

B

Gross error

C

Personal error

D

Random error

92

Which of the following is NOT one of the five base SI units commonly used in chemistry?

A

Length

B

Time

C

Mass

D

Volume

93

According to the text, why is it sensible to use grams rather than kilograms in a chemistry lab?

A

It is the official SI base unit

B

It provides more manageable numbers for calculation

C

It is more accurate than kilograms

D

It is required by international law

94

What is defined as the distance travelled by light in a vacuum in about 1/300,000,000 of a second?

A

Kilometer

B

Centimeter

C

Metre

D

Mile

95

The 'triple point of water' is a state where?

A

Water is boiling

B

Water is frozen solid

C

Water is in a plasma state

D

All three states of water exist at the same time

96

Why did scientists adopt a common system of units like SI?

A

To make science more exclusive

B

To ensure everyone can understand each other's measurements

C

To follow a historical tradition

D

To make calculations more complex

97

According to the text, what should you never do in a lab?

A

Wear a lab coat

B

Taste or smell any compound or gas directly

C

Ask the lab instructor for help

D

Check equipment before use

98

Chemicals that cause a sudden release of pressure, gas, and heat when shocked are called?

A

Flammable chemicals

B

Corrosive chemicals

C

Reactive chemicals

D

Explosive chemicals

99

Which of the following is an example of a flammable chemical?

A

Picric acid

B

Benzene

C

Water

D

Sodium chloride

100

What is the correct procedure when mixing concentrated acids with water?

A

Add water to acid rapidly

B

Add acid to water slowly

C

Mix them in any order

D

Heat the acid before mixing

CHEMISTRY MCQs

Compounds in which carbon atoms form only single bonds with other atoms are called?

Which family of hydrocarbons is the main subject of this chapter?

What is the general formula for alkanes?

In the IUPAC name for an organic compound, what does the 'root' part tell us?

The IUPAC root name 'Pent-' corresponds to how many carbon atoms?

What is the distinguishing feature of alkanes that makes them distinct from other compounds?

The reaction of alkanes with chlorine in the presence of sunlight is an example of what type of reaction?

What catalyst is used in the cracking of naphtha to produce smaller hydrocarbons?

The process of converting alkenes and alkynes to alkanes using hydrogen gas is called?

Which metal is used as a catalyst for the hydrogenation of ethene to ethane?

Alkanes are also referred to as paraffins, which means what?

The unreactivity of alkanes is explained by the ______ of their C-C and C-H bonds.

Complete combustion of any alkane produces which two substances?

What is the IUPAC name for the compound CH3-CH(CH3)-CH2-CH3?

The reduction of alkyl halides (R-X) to alkanes can be achieved using hydrogen generated by?

When methane reacts with excess chlorine, what is the final product?

Which term describes a reaction where one atom or group of atoms is replaced by another?

Hydrocarbons are organic compounds containing only which two elements?

Which of the following is a use for methane mentioned in the text?

In the IUPAC system, the part of the name that tells us about the class of organic compounds is the?

Which alkane cannot be prepared by the hydrogenation of alkenes or alkynes?

A structural formula shows the symbols for atoms connected by short lines which represent?

The reaction CH4 + 2O2 -> CO2 + 2H2O is an example of?

Which other atom is almost always present along with the carbon atom in all organic compounds?

Which metal can be used to reduce alkyl halides according to the options in the book's exercise?

If naphtha undergoes a combustion reaction, what products do you expect to form?

Why does a mixture of zinc and hydrochloric acid act as a reducing agent?

Which alkane will evolve the most amount of heat when it is burnt with oxygen?

Indicate the most reactive hydrocarbon from the given options.

Which hydrocarbon is responsible for explosions in coal mines?

Which product will be formed when ethyl bromide (C2H5Br) is treated with Zn/HCl?

Which of the following is not a process of halogenation of alkanes?

How many moles of oxygen will be required to completely burn propane?

Cracking of hydrocarbons is done at high temperature in the presence of a?

The process of cracking helps to balance the supply and demand of which product?

What is the IUPAC root for a chain of 7 carbon atoms?

The reaction of alkanes with halogens is carried out in the presence of?

Trichloromethane is also commonly known as?

The bonding electrons in C-H and C-C bonds are almost equally shared, making alkanes?

What is the condensed formula for methane?

Ethyne is reduced to ethane in the presence of Nickel catalyst at what temperature?

What type of formula is H-C(H)(H)-C(H)(H)-H?

Reduction of unsaturated compounds like alkenes is used to prepare?

The electronegativity value of carbon is given as?

The electronegativity value of hydrogen is given as?

A mixture of natural gas (methane) and air can do what when ignited?

In the IUPAC name 2-Methylbutane, 'methyl-' is the?

What is the primary reason scientists have agreed to adopt SI units?

SI units use a base number for easy conversion, just like our number system. What is that base number?

Which system of units is used almost everywhere in the world, allowing scientists to use a single standard for exchanging data?

Using SI units enables scientists to compare results, replicate experiments, and benefit from each other's work, which advances the frontiers of what?

How many base units are there in the SI system for physical quantities?

Which of the following is the standard unit of length in the SI system?

The kilogram (kg) is the standard unit of what physical quantity?

A kilogram is also defined as the mass of what volume of water?

What is the standard unit of time in the SI system, symbolized by 's'?

The unit 'second' is based on the radiation cycles of which atom?

What is the standard unit of temperature in the SI system, represented by K?

The Kelvin is defined as 1/273rd of the thermodynamic temperature of what?

What is the base unit for the amount of a pure substance, denoted by 'mol'?

A mole is defined as having exactly how many particles of a substance?

Which of the following is a derived unit in the SI system?

What is the derived unit for density in the SI system?

The unit for force, Newton (N), is derived from which combination of base units?

What does the SI prefix 'kilo' (k) represent?

Which SI prefix represents the fraction 10⁻³?

For what reason do chemists often measure the masses of reactants in grams?

Why is the Celsius scale often used in chemistry instead of the Kelvin scale?

What unit of volume is typically used in a chemistry lab for smaller quantities?

The level of uncertainty that every measurement carries is known as what?

An error can occur due to the limitation of the measuring instrument or the skill of the person making the measurement?

What type of error affects the accuracy of a measurement and can be removed by a constant adjustment?

A pipette or burette delivering a volume slightly different from its graduation is an example of what kind of error?

What type of error comes from unpredictable changes during an experiment and causes one measurement to differ slightly from the next?

Reading a volume from a measuring cylinder from a different angle each time is an example of a?

A random error often determines the what of the experiment?

What term measures how close results are to the true or known value?

The closeness of two or more measurements to each other is known as?

If you weigh a substance five times and get 3.2 kg each time, your measurement is considered what?