States of Matter NDA Questions

NDA Chemistry

States of Matter MCQ Questions


13.
According to Charles' Law, what is the physical significance of −273.15°C (absolute zero)?
A.
It is the temperature at which the volume of an ideal gas would theoretically become zero — all molecular motion ceases; it is the lowest theoretically possible temperature
B.
It is the temperature at which the pressure of all gases becomes zero at constant volume
C.
It is the melting point of water on the Kelvin scale
D.
It is the temperature at which all gases liquefy simultaneously
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ANSWER :
A. It is the temperature at which the volume of an ideal gas would theoretically become zero — all molecular motion ceases; it is the lowest theoretically possible temperature
14.
GAY-LUSSAC'S LAW (Amontons' Law) states that at constant volume, the pressure of a fixed amount of gas is:
A.
Independent of temperature at constant volume
B.
Inversely proportional to absolute temperature: P ∝ 1/T
C.
Directly proportional to the square root of temperature
D.
Directly proportional to absolute temperature: P ∝ T at constant V and n, i.e., P/T = constant (P₁/T₁ = P₂/T₂)
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ANSWER :
D. Directly proportional to absolute temperature: P ∝ T at constant V and n, i.e., P/T = constant (P₁/T₁ = P₂/T₂)
15.
AVOGADRO'S LAW states that at the same temperature and pressure, equal volumes of all gases contain:
A.
Equal number of molecules — V ∝ n at constant T and P, where n = number of moles (Avogadro's law, 1811)
B.
Equal number of atoms (regardless of molecule type)
C.
Equal masses of gas
D.
Equal number of electrons
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ANSWER :
A. Equal number of molecules — V ∝ n at constant T and P, where n = number of moles (Avogadro's law, 1811)
16.
The COMBINED GAS LAW (before Avogadro) relating P, V, and T for a fixed amount of gas is:
A.
P/VT = constant
B.
P₁V₁/T₁² = P₂V₂/T₂²
C.
P₁V₁T₁ = P₂V₂T₂
D.
PV/T = constant, i.e., P₁V₁/T₁ = P₂V₂/T₂
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ANSWER :
D. PV/T = constant, i.e., P₁V₁/T₁ = P₂V₂/T₂
17.
The IDEAL GAS EQUATION is:
A.
PV = NkT (equivalent — N is Avogadro's number; k is Boltzmann constant)
B.
PV = nRT, where P = pressure, V = volume, n = moles of gas, R = universal gas constant, T = absolute temperature
C.
PV = nR/T
D.
PV = mRT (where m = mass in grams)
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ANSWER :
B. PV = nRT, where P = pressure, V = volume, n = moles of gas, R = universal gas constant, T = absolute temperature
18.
The value of the Universal Gas Constant (R) in SI units is:
A.
R = 62.36 L·mmHg·mol⁻¹·K⁻¹
B.
R = 1.987 cal·mol⁻¹·K⁻¹
C.
R = 8.314 J mol⁻¹ K⁻¹ (= 8.314 Pa·m³·mol⁻¹·K⁻¹)
D.
R = 0.0821 L·atm·mol⁻¹·K⁻¹ (this is correct but NOT SI units)
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ANSWER :
C. R = 8.314 J mol⁻¹ K⁻¹ (= 8.314 Pa·m³·mol⁻¹·K⁻¹)