# Study of Gas Laws Exe-7 Structured Answer Chemistry Class-9 ICSE Selina Publishers

Study of Gas Laws Exe-7 Structured Answer Chemistry Class-9 ICSE Selina Publishers Solutions Chapter-7. Step By Step ICSE Selina Concise Solutions of Chapter-7 Study of Gas Laws with All Exercise including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type, Numerical and Structured/Application Questions Solved . Visit official Website CISCE for detail information about ICSE Board Class-9.

## Study of Gas Laws Exe-7 Structured Answer Chemistry Class-9 ICSE Concise Selina Publishers

 Board ICSE Publications Selina Publication Subject Chemistry Class 9th Chapter-7 Study of Gas Laws Book Name Concise Topics Solution of Exercise – 7 Structured/Application Answer Type Academic Session 2023-2024

### E. Exercise – 7 Structured/Application Answer Type

Study of Gas Laws Class-9 Chemistry Concise Solutions

Page-133

#### Question 1.

(a) State the law verified by the following figure:

(b) Draw P.V. isothermal for the above law.

(a) Boyle’s law — It states that the volume of a given mass of a dry gas is inversely proportional to its pressure at a constant temperature i.e., P1V1 = P2V2

(b) P.V. isothermal for Boyle’s law is shown below :

#### Question 2.

(a) State the law which the following graph verifies.

(b) Derive the mathematical expression for it.

(c) Give one application/use where the above law is employed.

(a) Charles’ law — It states that pressure remaining constant, the volume of a given mass of dry gas increases or decreases by 1/273 of its volume at 0°C for each 1°C increase or decrease in temperature, respectively.

(b) Let V0 be the volume of a fixed mass of a gas at 0°C and let V be its volume at temperature t°C at constant pressure. Then according to Charles’ law,

V = Vo + (Vo/273)t (when P is constant)

V = Vo (1 + t/273)

= Vo (273 + t)/273

V =V0/273 T where T = 273 + t

For a given mass of a gas,

V0/273 = constant

∴ V = k x T (where k is constant)

or V α T and V/T = K

Suppose a gas occupies V1 cm3 at T1 temperature and V2 cm3 at T2 temperature, then by Charles law,

V1 α T1

or V1 = kT1 (k is constant)

or
V1/T1 = k and

V2 α T2

or V2/T2 = k

∴ V1/T1 = V2/T2 = k (at constant pressure)

(c) Volume of a given mass of a gas is directly proportional to its temperature, hence, density decreases with an increase in temperature. This is the reason that hot air is filled into balloons used for meteorological purposes.

#### Question 3.

Plot V versus absolute T (K) by the given data:

Temperature Volume in litres
27°C 4.8
77°C 5.6
127°C 6.4
177°C 7.2
227°C 8.0

(a) The graph between V and T is a …………… .

(b) Check whether the line passes through the origin.

(c) Which law is obeyed.

Converting temperature to Kelvin Scale :

Temp
(°C)
Temp
(K)
Volume
(litres)
27 300 4.8
77 350 5.6
127 400 6.4
177 450 7.2
227 500 8.0

Graph of V versus absolute T is shown below :

(a) The graph between V and T is a straight line.

(b) Yes, as we can see in the graph, the line passes through the origin.

(c) Charles’ law

—  : End of Study of Gas Laws Exe-7 Structured Answer Class-9 ICSE Chemistry Solutions :–

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