[单选题]
A monatomic gas is cooy zwb3uwl 6e),led by 50 K at cyb.jn2j k(51yg:y 01f;z fmr iazvyj5onstant volume when 831 J of energy is removed from it. How many molb0yz;j 1vfn j5ygkya r .i 2(zm:yf15jes of gas are in the sample?
A. $2.50 \; mol$
B. $1.50 \; mol$
C. $1.33 \; mol$
D. none of the above
