Answer:
Yes, it is correct.
Explanation:
According to Newton's second law we have
[tex]\overrightarrow{F_{external}}=\frac{d\overrightarrow{p}}{dt}\\\\if\\\overrightarrow{F}_{external}=0\\\\\frac{d\overrightarrow{p}}{dt}=0\\\\\Rightarrow \overrightarrow{p}=constant[/tex]
It can also be understood as follows
Since no force acts on the system it's acceleration is zero and hence the velocity of the system does not change and hence the momentum is also conserved.