Q1 of 44 Page 1

Which of the following is not a physical change?

Combustion of Liquefied Petroleum Gas (LPG) is not a physical change. It is a chemical change because combustion of LPG produces new substances. A lot of heat is produced along with carbon dioxide and water vapour during this reaction. It is also irreversible in nature.


Rest three are physical changes as no new products are formed; the only state of the substance changes.


Note:


During a physical change, the physical state of substance changes. A physical change does not produce a new substance although the initial and final substances appear different. A physical change is reversible.


During a chemical change the chemical composition of substance changes. A chemical change produces a new substance with new properties. Energy is either released or absorbed during a chemical change. A chemical change is irreversible.

More from this chapter

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2

The following reaction is an example of a

4NH3 (g) +5O2 (g) → 4NO (g) +6H2O (g)


1. displacement reaction


2. combination reaction


3. redox reaction


4. neutralisation reaction

 3

Which of the following statements about the given reaction is correct?

3Fe(s) + 4H2O→ Fe3O4 + 4H2


a. Iron metal is getting oxidised.


b. Water is getting reduced.


c. Water is acting as reducing agent.


d. Water is acting as oxidising agent.

 4

Which of the following are exothermic processes?

1. Reaction of water with quick time


2. Dilution of an acid


3. Evaporation of water


4. Sublimation of camphor (crystals)

 5

Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of Na0H, anhydrous CuSO2 and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement (s) is (are) correct?

1. In beakers A and B, exothermic process has occurred.


2. In breakers A and B, endothermic process has occurred.


3. In breaker C, exothermic process has occurred.


4. In beaker C, endothermic process has occurred.