states-of-matter-quiz-6

States of Matter Quiz-6

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. The root mean square velocity of a gas is doubled when temperature is

•  Increased four times
•  Increased two times
•  Reduced to half
•  Reduced to one fourth

Solution
(a) v_rms=√(3RT/M) ∴ v_rms ∝ √T ∴ At two different temperatures, v_rms/(v_rms' )=√(T/T' ) Given, v'_rms=2v_rms 1/2=√(T/T' ) or 1/4=T/T' ∴ T'=4T ∴v_rms gets doubled, when the temperature is increased four times.  

Q2.While He is allowed to expand through a small jet under adiabatic condition heating effect is observed. This is due to the fact that:

•  Helium is an inert gas
•  Helium is a noble gas
•  Helium is an ideal gas
•  The inversion temperature of helium is very low

Solution

(d) Heating effect is noticed on subjecting a gas for Joule-Thomson effect above its inversion temperature.

Q3. A crystalline solid 

•  Changes abruptly from solid to liquid when heated
•  Has no definite melting point
•  Has an irregular three-dimensional arrangements
•  Undergoes deformation of its geometry easily

Solution
(a) A crystalline substance has a sharp melting point ie, solid changes abruptly into liquid state

Q4. If the absolute temperature of a gas is doubled and the pressure is reduced to one half, the volume of the gas will

•  Remain unchanged
•  Be doubled
•  Increase four fold
•  Be halved

Solution
(c) For a gas, 

 (p₁ V₁)/T₁ =(p₂ V₂)/T₂ (where,T₂=2T₁,p₂=1/2 p₁,V₂=?) 

 (p₁ V₁)/T₁ =1/2 (p₁×V₂)/(2T₁ ) 

 V₁=V₂/4 V₂=4V₁

Q5.Point defects are present in

•  ionic solids
•  amorphous solids
•  molecular solids
•  Liquids

Solution
  (a) ionic solids  

Q6. If pressure of a gas contained in a closed vessel is increased by 0.4% when heated by 1℃ its initial temperature must be:

•  250 K
•  250℃
•  2500 K
•  25℃

Solution
(a) T₂=T₁+1; P₂=P₂+(0.4 P₁)/100 Now use, (P₁ V₁)/T₁ =(P₂ V₂)/T₂ assuming V₁=V₂  

Q7.The critical temperature of a gas is that temperature:

•  Above which it can no longer remain in the gaseous state
•  Above which it cannot be liquefied by pressure
•  At which it solidifies
•  At which volume of gas becomes zero

Solution

(b) Follow definition of critical temperature.

Q8.Indicate which of the following statements is correct?

•  At constant temperature, the KE of all gas molecules will be the same
•  At constant temperature, the KE of different molecules will be different
•  At constant temperature, the KE will be greater for heavier gas molecules
•  At constant temperature, the KE will be less for heavier gas molecules

Solution
(a) At constant temperature, the KE of all gas molecules will be the same 

Q9.In the Bragg’s equation for diffraction of X-rays, n represents for

•  Avogadro’s number
•  quantum number
•  Moles
•  an integer

Solution

(d) an integer

Q10. The rate of diffusion of hydrogen gas is

•  1.4 times to He gas
•  Same as He gas
•  5 times to He gas
•  2 times to He gas

Solution

(a) We know that molecular mass of hydrogen (M₁ )=2 and that of helium (M₂ )=4. We also know that Graham’s law of diffusion r₁/r₂ =√(M₂/M₁ )=√(4/2)=√2=1.4 r₁=1.4 r₂