Prepare for your exams with the Class 10 Chemistry Chapter 14 Full Unit Test 7, based on the topic State of Matter and Phase Changes. These Punjab Board 2027 Model Papers are designed to help students practise important chemistry questions according to the latest syllabus and paper pattern. This Class 10 Chemistry unit test covers key concepts, including kinetic particle theory, states of matter, evaporation, boiling, sublimation, diffusion, gas laws, and phase changes. Students can use this full unit test for exam preparation, revision, self-assessment, and practice for the Punjab Boards Annual Examination 2027.
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Note: Four possible answers A, B, C and D to each
question are given. The choice which you think is correct, fill
that circle in front of that question with Marker or Pen ink.
Cutting or filling two or more circles will result in zero mark
in that question.
1. According to kinetic particle theory,
gas particles are always in:
(a) circular motion
(b) vibratory motion
(c) random motion
(d) fixed positions
2. Evaporation occurs:
(a) only at boiling point
(b) only at high temperature
(c) at all temperatures
(d) Only at low temperature
3. For water, the temperature remains constant
at 0°C because:
(a) Heat is lost to surroundings
(b) Ice starts boiling
(c) Water starts Boiling
(d) Ice is melting into water
4. The energy required for sublimation comes from:
(a) an external heat source only
(b) inside the substance itself
(c) surrounding pressure
(d) atmospheric moisture
5. Upon heating the rate of evaporation:
(a) decreases
(b) increases
(c) remains the same
(d) initially decreases and then increases upon further heating
6. Cooling the vapours of some gases change them
directly into solid state. This phenomenon is called:
(a) evaporation
(b) condensation
(c) sublimation
(d) deposition
7. Physical state in which the particles possess
the maximum energy:
(a) Solid
(b) Liquid
(c) Gaseous
(d) Vapour
8. The phase changes A and B in
gas
A
→
liquid
B
→
solid
are:
(a) Melting, evaporating
(b) Condensation, melting
(c) Condensation, freezing
(d) Boiling, freezing
9. The process of conversion of gas into liquid
at constant temperature is called:
(a) Evaporation
(b) Freezing
(c) Condensation
(d) Sublimation
10. Naphthalene balls disappear when kept in
cupboards because they:
(a) melt slowly
(b) evaporate
(c) condense
(d) sublime
11. The spreading of fragrance in air is due to:
(a) melting of the solid
(b) diffusion of vapours
(c) freezing of vapours
(d) condensation of vapours
12. Which of the following conditions remained
constant during Boyle’s experiment?
(a) Pressure
(b) Volume
(c) Temperature
(d) Density
HERE IS Subjective Part of Paper.
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Part – I
2.
Write short answers to any Five (5) questions:
[5×2=10]
(i)
Why solids have fix shape and fix volume?
(ii)
How does the arrangement of particles differ between the solid
and liquid?
(iii)
Why can evaporation occur at all temperatures?
(iv)
Why does heating a liquid increase the rate of evaporation?
(v)
What is a heating curve?
(vi)
What is evaporation? How can it be observed in an open
container of water?
(vii)
Why the boiling point of water decreases at higher altitudes.
(viii)
How does a solid air freshener release fragrance into the air?
3.
Write short answers to any Five (5) questions:
[5×2=10]
(i)
Define Boyle’s Law. Write its mathematical equation.
(ii)
State Avogadro’s law.
(iii)
Why hydrogen gas diffuses faster than oxygen gas at the same
temperature.
(iv)
How diffusion influences the effectiveness of drug after
absorption.
(v)
Why are lipid-soluble drugs generally more effective in a
shorter time?
(vi)
Is the average kinetic energy possessed by the particles of a
gas and a liquid, same at the same temperature?
(vii)
Why do water vapour at 100°C cause more severe burns as compared
to liquid water at the same temperature?
4.
Write short answers to any Five (5) questions:
[5×2=10]
(i)
Why do naphthalene balls (used to repel insects) disappear
after sometime?
(ii)
Why does the temperature remain constant during a phase change?
(iii)
Can you change the temperature at which water boils in an
experiment in your lab?
(iv)
When a solid is heated, what happens to its vibrating particles?
(v)
Differentiate between evaporation and boiling.
(vi)
Describe how boiling is related to the external pressure.
(vii)
Why do the heating and cooling curves for phase changes adopt
the same path?
(viii)
Why do phase changes occur?
Part – II
NOTE:- Attempt any two questions.
[9×2=18]
5.
(a)
How does the process of sublimation helpful in printing and
in the usage of air freshener?
(b)
Explain boiling process. Write its characteristics.
6.
(a)
Draw heating curve for the physical changes water undergoes
with change in temperature.
(b)
Discuss Avogadro’s law with the help of kinetic particle theory.
7.
(a)
Explain the difference in the rates of diffusion of two gases
based on kinetic theory.
(b)
How a liquid is converted into a gas.
