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Previous Year Questions Of Physical and Chemical Changes & Elements, Mixtures and Compounds for NDA

NDA Previous Year Questions

Q 2119323219

Which one of the following is not a chemical change?.
NDA Paper 2 2016
(A)

Ripening of fruits

(B)

Curdling of milk

(C)

Freezing of water

(D)

Digestion of food

Solution:

Freezing of water is a physical change, i.e. not a

chemical change because it is the interconversion of

states, the physical property changes but the chemical

composition remains the same.
Correct Answer is `=>` (C) Freezing of water
Q 1610767619

Matter around us can exist in three different states
namely, solid, liquid and gas. Correct order of their
compressibility is
NDA Paper 1 2016
(A)

Liquid < Gas < Solid

(B)

Solid < liquid < Gas

(C)

Gas < Liquid < Solid

(D)

Solid < Gas < Liquid

Solution:

The correct order of compressibility is Solid < Liquid < Gas

. Gases are highly compressible as compared to

solids and liquids. In gas, the molecules have enough

kinetic energy so that the effect of intermolecular

forces is small and the typical distance between

neighbouring molecules is much greater than the

molecular size.
Correct Answer is `=>` (B) Solid < liquid < Gas
Q 2119323219

Which one of the following is not a chemical change?.
NDA Paper 2 2016
(A)

Ripening of fruits

(B)

Curdling of milk

(C)

Freezing of water

(D)

Digestion of food

Solution:

Freezing of water is a physical change, i.e. not a

chemical change because it is the interconversion of

states, the physical property changes but the chemical

composition remains the same.
Correct Answer is `=>` (C) Freezing of water
Q 2158123004

The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point. The melting point of a solid is an indication of.
NDA Paper 2 2016
(A)

strength of the intermolecular forces of attraction

(B)

strength of the intermolecular forces of repulsion

(C)

molecular mass

(D)

molecular size

Solution:

The melting point of a solid is an indication of

strength of intermolecular force of attraction. On

increasing the temperature of solids, the kinetic

energy of the particles increases. Due to the increase

in kinetic energy, the particles start vibrating with

greater speed. The energy supplied by the heat

overcomes the forces of attraction between the

particles. A stage is reached when solid melts and is

converted to a liquid.
Correct Answer is `=>` (A) strength of the intermolecular forces of attraction
Q 2108723608

When a solid is heated, it turns directly into a gas. This process is called.
NDA Paper 2 2016
(A)

Condensation

(B)

Evaporation

(C)

Sublimation

(D)

Diffusion

Solution:

Sublimation is the change of state from solid state

directly to gaseous state without going through

liquid state and vice - versa.
Correct Answer is `=>` (C) Sublimation
Q 1720512411

A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo
NDA Paper 2 2014
(A)

a change in mass

(B)

a change in density

(C)

a change in composition

(D)

no change in physical properties

Solution:

A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo a change in density.
Correct Answer is `=>` (B) a change in density
Q 1720512411

A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo
NDA Paper 2 2014
(A)

a change in mass

(B)

a change in density

(C)

a change in composition

(D)

no change in physical properties

Solution:

A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo a change in density.
Correct Answer is `=>` (B) a change in density
Q 1752567434

The latest discovered state of matter is
1976
(A)

solid

(B)

Bose-Einstein condensate

(C)

plasma

(D)

liquid

Solution:

There are four states of matter, which are given solid, liquid, gas and plasma. Plasma is the latest discovered state of matter.
Correct Answer is `=>` (C) plasma
Q 2346180973

A mixture of sodium chloride and naphthalene can be separated by
NDA Paper 2 2013
(A)

extraction with hot water

(B)

extraction with cold water

(C)

sublimation

(D)

steam distillation

Solution:

Naphthalene is a sublimate. A sublimate is a substance
which changes directly from the solid state to the gaseous state
and vice-versa. So, by utilising this property, we can separate the
mixture of sodium chloride and naphthalene by heating it. The
naphthalene will sublimate and we will be left with sodium
chloride.
Correct Answer is `=>` (C) sublimation
Q 2366080875

The following items consist of two statements, Statement I and Statement II. You are required to examine these two statements carefully.
Statement I Glass is not considered as a true compound.
Statement II Glass does not have a definite melting point.
NDA Paper 2 2013
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true, but Statement II is not t11e correct explanation of Statement It

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true

Solution:

Glass is an amorphous (non-crystalline) solid amorphous solids do not have a definite melting point or regular repeating units. An example of on amorphous solid is window glass.
Correct Answer is `=>` (A) Both the statements are true and Statement II is the correct explanation of Statement I
Q 2386191077

Metalloids are
NDA Paper 2 2013
(A)

alloys of alkali metals with other metals

(B)

colloids of metals

(C)

elements having some properties of both metals and non-metals

(D)

metals heavier than lead

Solution:

A metalloid is a chemical element that has properties that are in between or a mixture of those of metals and non-metals and is consequently difficult to classify unambiguously as either a metal or a non-metal. The six elements commonly recognised as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium.
Correct Answer is `=>` (C) elements having some properties of both metals and non-metals
Q 2387045887

Air is
NDA Paper 2 2012
(A)

always a compound

(B)

always a mixture

(C)

a compound in pollution-free zones

(D)

a mixture in industrial zones

Solution:

Air is the name given to atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) `78.09%`, nitrogen, `20.95%` oxygen, `0.93%` argon, `0.039%` carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around `1%.`
Correct Answer is `=>` (B) always a mixture
Q 2826023871

Statement I Conversion of blue copper sulphate to black cupric oxide on heating is a physical change.

Statement II A change in which chemical composition does not change is called physical change.
NDA 2012
(A)

Both the statements are true and Statement II is the correct explanation of Statement I

(B)

Both the statements are true but Statement II is not the correct explanation of Statement I.

(C)

Statement I is true, but Statement II is false

(D)

Statement I is false, but Statement II is true.

Solution:

Air is the name given to atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) `78.09%`, nitrogen, `20.95%` oxygen, `0.93%` argon, `0.039%` carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around `1%.`
Correct Answer is `=>` (D) Statement I is false, but Statement II is true.
Q 2846023873

Statement I The bule colour of copper sulphate crystal disappears when it is heated strongly.

Statement II Due to heating water of crystallisation of crystal is lost.
NDA 2012
(A)

Both the statements are true and Statement II is the correct explanation of Statement I.

(B)

Both the statements are true but Statement II is not the correct explanation of Statement I.

(C)

Statement I is true, but Statement II is false.

(D)

Statement I is false, but Statement II is true.

Solution:

Air is the name given to atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) `78.09%`, nitrogen, `20.95%` oxygen, `0.93%` argon, `0.039%` carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around `1%.`
Correct Answer is `=>` (A) Both the statements are true and Statement II is the correct explanation of Statement I.
Q 2317278180

Which one among the following is not a mixture?
NDA Paper 2 2011
(A)

Graphite

(B)

Glass

(C)

Brass

(D)

Steel

Solution:

Element is a pure substance that contains only one
kind of atoms. Graphite is the crystalline allotrope of carbon. On
the other hand mixture contains two or more substances in any
proportions. e.g., glass is a homogeneous mixture of silicates or
borosilicates of metals in silica, brass is a mixture of copper and
zinc, steel is a mixture of iron, nickel, chromium and carbon.
Correct Answer is `=>` (A) Graphite
 
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