Online Test — States of Matter
20 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 20
Boyle’s law is valid at constant:
volume
temperature
pressure
density
Explanation: Boyle’s law relates $P$ and $V$ at constant temperature: $PV=\text{constant}$.
Question 2 of 20
The ideal gas equation is:
$PV=nRT$
$PVT=nR$
$\frac{PV}{T}=nR^2$
$P=nRTV$
Explanation: The ideal gas equation combines all four gas laws into $PV=nRT$.
Question 3 of 20
According to Charles’ law, at constant pressure volume is proportional to:
$\frac{1}{T}$
absolute temperature $T$
$T^2$
pressure
Explanation: $\frac{V}{T}=\text{constant}$, so $V\propto T$ (in kelvin).
Question 4 of 20
Equal volumes of gases at the same $T$ and $P$ contain equal numbers of molecules. This is:
Boyle’s law
Avogadro’s law
Dalton’s law
Graham’s law
Explanation: Avogadro’s law: $V\propto n$ at fixed $T,P$.
Question 5 of 20
Hydrogen bonding is strongest when H is bonded to:
C
S
Cl
F
Explanation: Among the listed atoms only F (highly electronegative and small) gives true hydrogen bonding.
Question 6 of 20
The value of $R$ in $\text{L atm mol}^{-1}\text{K}^{-1}$ is:
8.314
0.0821
1.38
6.022
Explanation: $R=0.0821\ \text{L atm mol}^{-1}\text{K}^{-1}=8.314\ \text{J mol}^{-1}\text{K}^{-1}$.
Question 7 of 20
In Dalton’s law, the partial pressure of a gas equals:
$x_i P_{total}$
$\frac{P_{total}}{x_i}$
$P_{total}-x_i$
$x_i + P_{total}$
Explanation: $p_i=x_i P_{total}$, with $x_i$ the mole fraction.
Question 8 of 20
The average translational kinetic energy of a molecule is:
$\frac{1}{2}k_BT$
$k_BT$
$\frac{3}{2}k_BT$
$3k_BT$
Explanation: Kinetic theory gives $\overline{KE}=\frac{3}{2}k_BT$ per molecule.
Question 9 of 20
The rms speed of a gas is:
$\sqrt{\frac{2RT}{M}}$
$\sqrt{\frac{3RT}{M}}$
$\sqrt{\frac{8RT}{\pi M}}$
$\frac{3RT}{M}$
Explanation: By definition $u_{rms}=\sqrt{\frac{3RT}{M}}$.
Question 10 of 20
The correct order of molecular speeds is:
$u_{rms}
$u_{avg}
$u_{mp}
all equal
Explanation: The fixed ratio $1:1.128:1.224$ gives $u_{mp}
Question 11 of 20
If the temperature of a gas is increased four times, the rms speed becomes:
twice
four times
half
sixteen times
Explanation: $u_{rms}\propto\sqrt{T}$, so $\sqrt{4}=2$: the speed doubles.
Question 12 of 20
On the Maxwell–Boltzmann curve, raising temperature makes the peak:
sharper and shift left
flatter and shift right
unchanged
vanish
Explanation: Higher $T$ shifts the most-probable speed to a higher value and broadens (flattens) the curve.
Question 13 of 20
The compressibility factor for an ideal gas equals:
0
0.5
1
2
Explanation: $Z=\frac{PV}{nRT}=1$ for an ideal gas.
Question 14 of 20
When attractive forces dominate, the compressibility factor is:
$Z>1$
$Z<1$
$Z=1$
$Z=0$
Explanation: Attractions reduce the actual volume below ideal, so $Z<1$ (typically at low pressure).
Question 15 of 20
In the van der Waals equation, $b$ corrects for:
intermolecular attraction
finite molecular volume
temperature
pressure units
Explanation: The $nb$ term subtracts the volume occupied by molecules themselves.
Question 16 of 20
A gas cannot be liquefied by pressure above its:
boiling point
melting point
critical temperature
triple point
Explanation: Above $T_c$, no pressure can produce a liquid.
Question 17 of 20
The critical volume $V_c$ in terms of the van der Waals constant $b$ is:
$b$
$2b$
$3b$
$\frac{b}{3}$
Explanation: Solving the van der Waals critical conditions gives $V_c=3b$.
Question 18 of 20
As temperature rises, the viscosity of a liquid:
increases
becomes infinite
stays constant
decreases
Explanation: Higher temperature gives molecules more energy to slide past each other, lowering viscosity.
Question 19 of 20
A liquid boils when its vapour pressure becomes equal to:
zero
the external pressure
its critical pressure
the atmospheric density
Explanation: Boiling occurs when vapour pressure equals the surrounding (external) pressure.
Question 20 of 20
At the same temperature, which gas has the highest rms speed?
$\text{O}_2$
$\text{N}_2$
$\text{H}_2$
$\text{CO}_2$
Explanation: At fixed $T$, $u_{rms}\propto\frac{1}{\sqrt{M}}$; hydrogen has the smallest molar mass.
Vidaara uses essential cookies to run the site and, with your consent, optional cookies to understand how learners use Vidaara so we can improve it. We never sell your data. Read our Cookie Policy and Privacy Policy.