NEET and AIPMT NEET Chemistry States of Matter MCQ Questions Solved

NEET - 2016

Equal moles of hydrogen and oxygen gases are placed in container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape?

(a) 1/4          (b) 3/8          (c) 1/2            (d) 1/8

(d) Given, number of moles of hydrogen (nH2) and that of oxygen (nO2) are equal.

... We have, the relation between ratio of number of moles escaped and ratio of molecular mass.

                 nH2nO2=MH2MO2

where, M = Molecular mass of the molecule

               nO2nH2=232=116

                nO20.5 = 14

                 nO2= 0.5/4 =1/8

Difficulty Level:

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NEET - 2015

A gas such as carbon monoxide would be most likely to obey the ideal gas law at

(a) high temperatures and low pressures

(b) low temperatures and high pressures

(c) high temperatures and high pressures

(d) low temperatures and low pressures

Real gases show ideal gas behaviour at high temperature and low pressures.

Difficulty Level:

  • 60%
  • 29%
  • 8%
  • 5%
NEET - 2014

Equal masses of H2, O2 and methane have been taken in a container of volume V at temperature 27°C in identical conditions. The ratio of the volumes of gases H2: O2 : CH4 would be
(a) 8:16:1

(b) 16:8:1

(c) 16:1:2

(d) 8:1:2

(c) According to Avogadro's hypothesis, Volume of a gas (V)  number of moles (n)

Therefore, the ratio of the volumes of gases can be determined in terms of their moles. The ratio of volumes of H2: O2:methane (CH4)
is given by

        VH2 :VO2: VCH4 = nH2 :nO2 : nCH4 VH2 :VO2: VCH4 = mH2MH2 : mO2MO2 : mCH4MCH4But mH2 = mO2 = mCH4 = m2 :m32: m16 = 16:1:2

Difficulty Level:

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NEET - 2014

When 22.4 L of H2 (g) is mixed with 11.2 L of Cl2 (g), each at STP, the moles of HCl(g) formed is equal to

(a)  1 mole of HCl (g)

(b) 2 moles of HCl (g)

(c) 0.5 mole of HCl (g)

(d) 1.5 mole of HCl (g)

The given problem is related to the concept of stiochiometry of chemical equations. Thus, we have to convert the given volumes into their moles and then, identify the limiting reagent [possessing minimum number of moles and gets completely used up in the reaction].

The limiting reagent gives the moles of product formed in the reaction.

              H2(g) + Cl2(g) 2HCl (g)

Initial vol   22.4 L    11.2 L      2 mol

... 22.4 L volume at STP is occupied by,

              Cl2 = 1 mole,

... 11.2 L volume will be occupied by,

             Cl2 = 1x 11.2/22.4 mole = 0.5 mol

Thus, H2(g) + Cl2(g) 2HCl (g)

 

 

 

 

 

 

 

Difficulty Level:

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NEET - 2013

Maximum derivation from ideal gas is expected from:

(a) H2(g)   

(b) N2(g)

(c) CH2(g)

(d) NH3(g)

(d) Easily liquefiable gases like NH3, SO2 etc. exhibit maximum deviation from ideal gas as for them Z<<< 1 .

CH4  also exhibits deviation but it is less as compared to NH3.

Difficulty Level:

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NEET - 2011

A gaseous mixture was prepared by taking equal moles of CO and N2. If the total pressure of the mixture was found 1 atmosphere, the partial pressure of the nitrogen (N2) in the mixture is

(a) 0.8 atm

(b) 0.9 aim

(c) 1 atm

(d) 0.5 atm

"CO="N2 

Pco = PN2 

Given, Pco + PN2 = 1atm 

or       2PN2 = 1 atm

or        PN2 = 0.5atm  

Difficulty Level:

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NEET - 2011

Two gases A and B having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of A is 49 u. Molecular mass of B will be

(a) 12.25 u
(b) 6.50 u
(c) 25.00 u
(d) 50.00 u

 

 

(a)

 VAVB = MBMAor VAtA ×tBVB = MBMAor 1020 = MB49or   14 = Ma49 MB = 494 = 12.25 u.

 

Difficulty Level:

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NEET - 2011

By what factor does the average velocity of a gaseous molecule increase when the temperature (in Kelvin) is doubled?

(a) 2.8

(b) 4.0

(c) 1.4

(d) 2.0

Average velocity = 8RTπM

Vav α T

or (Vav)2 / (Vav )12TT = 1.4

Difficulty Level:

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NEET - 2008

If a gas expands at constant temperature, it indicates that

(a) kinetic energy of molecules decreases

(b) pressure of the gas increases

(c) kinetic energy of molecules remains the same

(d) number of the molecules of gas increases

Key Idea: KE = 3/2RT

KE ∝ T

Here, the temperature of gas remains constant, hence kinetic energy of molecules remains the same.

Difficulty Level:

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NEET - 2008

What volume of oxygen gas (O2) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C3H8) measured under the same conditions?

(a) 7L

(b) 6L

(c) 5L

(d) 10L

Key Idea: Volume of a gas STP = 22.4L

To burn 22.4 L C3H8 the oxygen required is = 5 x 22.4 L

To burn 1 LC3H8 the oxygen required will be = 5 x 22.4 / 22.4 = 5L

Difficulty Level:

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