Physical and Chemical Changes, Solution – Old Year Questions

1. An example of physical change –

(a) Blackening of silverware
(b) Burning of Candle
(c) Making of curd from milk
(d) Dissolving of sugar in water

[38th B.P.S.C. (Pre) 1992]


2. The change of water into the vapour is called –

(a) Natural
(b) Physical
(c) Chemical
(d) Biological

[U.P.P.C.S. (Pre) 1992]


3. Which of the following is an example of chemical change–

(a) Dispersion of white light into the light of 7 colours when passed through a prism
(b) Softening of vegetables when cooked
(c) Wet soil lump, when dried, gets fragile
(d) Dissolving of salt in water

[R.A.S./R.T.S. (Pre) 2003]


4. Which of the following is/are the example/examples of chemical change?
1. Crystallization of sodium chloride
2. Melting of ice
3. Souring of milk
Select the correct answer using the code given below.

(a) 1 and 2 only
(b) 3 only
(c) 1, 2 and 3
(d) None

[I.A.S. (Pre) 2014]


5. Assertion (A): A chemical reaction becomes faster at a higher temperature.
Reason (R): At higher temperatures, molecular motion becomes more rapid.

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not a correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.

[I.A.S. (Pre) 2001]


6. What form of energy is produced in the decomposition of water?

(a) Light
(b) Heat
(c) Sound
(d) Acid

[M.P.P.C.S. (Pre) 1997]


7. Pasteurization is a process by which –

(a) Milk is preserved at a very low temperature for 24 hours
(b) Milk is heated for 8 hours
(c) First milk is heated up for a longer time and then cooled suddenly within the specified time
(d) None of these

[38th B.P.S.C. (Pre) 1992]


8. Pasteurization is related to :

(a) Sterilization of milk
(b) Dehydration of milk
(c) Fermentation of milk
(d) Distillation of milk

[M.P. PCS (Pre) 2016]


9. Which of the following is NOT correctly matched?

(a) Desalination Seawater
(b) Reverse osmosis Potable water
(c) Denaturation Proteins
(d) Pasteurization Tea

[U.P.P.C.S. (Pre) 2019]


10. Because of impurities the boiling point of a liquid –

(a) Increases
(b) Decreases
(c) Remains constant
(d) They are not related

[M.P.P.C.S. (Pre) 2004]


11. Give a thought to these statements :
Statement (A): Temperature below 0o C is achieved by the mixture of salt and ice.
Reason (R): Salt increases the freezing point of ice. In the context of the above statements which one of the following is correct:

(a) (A) and (R) are both correct, and (R) is the correct explanation of (A).
(b) (A) and (R) are both correct, but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is wrong.
(d) (A) is wrong but (R) is correct.

[U.P. Lower Sub. (Pre) 1998, I.A.S. (Pre) 1993]


12. Milk is an example of :

(a) A gel
(b) A foam
(c) An emulsion
(d) A suspension

[42nd B.P.S.C. (Pre) 1997, U.P.P.C.S. (Pre) 1996]


13. Which of these is not a colloid :

(a) Milk
(b) Blood
(c) Icecream
(d) Honey

[U.P.P.C.S. (Pre) 2002]


14. Which type of colloidal system is expressed in the fog :

(a) Liquid in a gas
(b) Gas in a liquid
(c) Solid in a gas
(d) Liquid in Liquid

[I.A.S. (Pre) 1993]


15. If an unsaturated sugar solution is prepared by mixing 100 grams of sugar with half a litre of water, which of the following physical quantities will not change?

(a) Mass
(b) Density
(c) Concentration
(d) Volume

[U.P.P.C.S. (Pre) 2017]


16. After cutting the cucumber if salt is added, then water comes out due to :

(a) Active transport
(b) Passive transport
(c) Osmosis
(d) Difusion

[U.P. P.C.S. (Pre) 2021]


17. Consider the following statements :
1. During the process of osmosis, the solvent travels from the concentrated solution to the dilute solution.
2. In reverse osmosis, external pressure is applied to the dilute solution.
Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

[I.A.S. (Pre) 2005]


18. Which one of the following processes is NOT useful for the purification of solid impurities?

(a) Distillation
(b) Sublimation
(c) Crystallization
(d) All of the above

[U.P. R.O./A.R.O. (Pre) (Re. Exam) 2016]


19. The technique of chromatography is used to –

(a) Identify colour substances
(b) Determine the structure of substances
(c) Dry distillation of colouring substances
(d) Separate the substances from a mixture

[42nd B.P.S.C. (Pre) 1997]


20. The process of solid camphor into camphor vapour is called:

(a) Vaporization
(b) Freezing
(c) Melting
(d) Sublimation

[44th B.P.S.C. (Pre) 2000]


21. A sample of any of the following substances disappears after some time when exposed to air like camphor, naphthalene or dry ice. This phenomenon is called :

(a) Sublimation
(b) Evaporation
(c) Diffusion
(d) Radiation

[U.P.P.C.S. (Pre) 2019]


22. The conversion of a solid directly into gas is called as :

(a) Sublimation
(b) Condensation
(c) Evaporation
(d) Boiling
(e) None of the above/More than one of the above

[63rd B.P.S.C. (Pre) 2017]


23. A mixture of sand and naphthalene can be separated by :

(a) sublimation
(b) distillation
(c) chromatography
(d) fractional distillation
(d) None of the above / More than one of the above

[66th B.P.S.C. (Pre) 2020]


24. Match List-I (oxidation number) with List-II (the element) and select the correct answer using the codes given below the lists :
List-I                        List-II
A. 2 1.          Oxidation number of Mn in MnO2
B. 3 2.         Oxidation number of S in H2 SO4
C. 4 3.         Oxidation number of Ca in CaO
D. 6 4.         Oxidation number of Al in NaAlH4
Code :

(a) 3 4 1 2
(b) 4 3 1 2
(c) 3 4 2 1
(d) 4 3 2 1

[I.A.S. (Pre) 2002]


25. An example of corrosion is –

(a) Black coating on Silver
(b) Green coating on Copper
(c) Brown coating on Iron
(d) Above three
(e) None of the above

[Chhattisgarh P.C.S. (Pre) 2016]