states-of-matter-quiz-10

States of Matter Quiz-10

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry..

Q1. A gaseous mixture was prepared by taking equal mole 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:

•  1 atm
•  0.5 atm
•  0.8 atm
•  0.9 atm

Solution
P'_N2=P_T×mole fraction of N₂ =1×1/(1+1)=1/2  

Q2.At what temperature will most probable speed of the molecules of the second number of alkyne series be the same as that of SO₂ at 527℃?

•  347℃
•  227℃
•  800℃
•  254℃

Solution

(b) Second member of alkyne series is C₃ H₄.(m-40) C₃ H₄ SO₂ √((2RT₁)/M₁ )=√((2RT₂)/M₂ ) T₁=T₂ (M₁/M₂ )=800 (40/64)K =500 K=227℃

Q3. In van der Waals’ equation of state of the gas, the constant 'b' is a measure of: 

•  Intermolecular collisions per unit volume
•  Intermolecular attraction
•  Volume occupied by molecules
•  Intermolecular repulsions

Solution
(c) b=4×N× volume of one molecule in rest.

Q4. The value of gas constant R in SI unit is:

•  83 erg K^-1 mol^-1
•  0.082 litre atm
•  8.3 J K^-1 mol^-1
•  0.987 cal K^-1 mol^-1

Solution
(c) R=PV/nT;R=8.3JK^-1 mol^{-1=2 cal K-1 mol-1 =8.314 erg K-1 mol-1=0.821 litre atm K-1 mol-1}

Q5.At absolute zero:

•  Gaseous phase does not exist
•  Molecular motion ceases
•  Temperature is -273℃
•  All of the above

Solution
  (d) These are characteristics observed at absolute zero.  

Q6. At constant temperature, in the given mass of an ideal gas

•  The ratio of pressure and volume always remains constants
•  Volume always remains constant
•  Pressure always remains constant
•  The product of pressure and volume always remains constant

Solution
(d) For a fixed amount of gas at constant temperature, the gas volume is inversely proportional to the gas pressure. Thus pV=constant  

Q7.a and b are van der Waals’ constants for gases. Chlorine is more easily liquefied than ethane because

•  a and b for Cl₂>a and b for C₂ H₆
•  a and b for Cl₂<a and b for C₂ H₆
•  a for Cl₂>a for C₂ H₆ but b for Cl₂>b for C₂ H₆
•  a for Cl₂>a for C₂ H₆ but b for Cl₂<b for C₂ H₆

Solution

(d) van der Waals’ constant a is due to force of attraction and b due to finite size of molecules. Thus greater the value of a and smaller the value of b, larger the liquefaction. Thus, a(Cl₂ )>a(C₂ H₆ )   

and b (Cl₂ )>b (C₂ H₆ )

Q8.If C₁,C₂,C₃,… represent the speeds of n₁,n₂,n₃,… molecules, then the root mean square speed is:

•  
  
  
•  
  
  
•  
  
  
•  
  
  

Solution
(a) It is the desired formula for u_rms.  

Q9.Potassium fluoride has NaCl type structure. What is the distance between K⁺ and F^- ions if cell edge is a cm?

•  a/2 cm
•  a/4 cm
•  2a cm
•  4a cm

Solution

(a) Distance between K⁺ and F^-=1/2× length of the edge

Q10. Consider an ideal gas contained in a vessel. If the intermolecular interactions suddenly begins to acts, which of the following will happen?

•  The pressure decrease
•  The pressure increase
•  The pressure remains unchanged
•  The gas collapses

Solution

(a)The pressure decrease