For a gas with $Z = 1 + B^{'} P$ at low pressure, where $B^{'}$ is negative at $T_{1}$ and positive at $T_{2}$ , which statements are correct?

A $T_{1}$ is less than the Boyle temperature and $T_{2}$ is greater than it
BAt $T_{1}$ the molar volume is smaller than the ideal value at the same pressure
CAt $T_{2}$ the gas is less compressible than an ideal gas
DThe product $P V_{m}$ at $T_{1}$ decreases with increasing $P$ at low pressure

Answer: A, B, C, D

Negative

B^{'}

means attraction dominates, which occurs below

T_{B}

; positive

B^{'}

occurs above (A true). At

T_{1}

Z

is less than 1, so

V_{m}

is below the ideal value (B true). At

T_{2}

Z

exceeds 1 and the gas resists compression more than an ideal gas (C true).

P V_{m} = RT (1 + B^{'} P)

falls with

P

when

B^{'}

is negative (D true).