Chopra took his tally to the new season to six with a goal in the first five minutes and two more in the last ten as Dave Jones' side maintained their unbeaten start to the campaign.
City took the lead after less than four minutes when Jay Bothroyd broke free on the right wing before cutting the ball back to an unmarked Chopra, who chipped the ball over Argyle goalkeeper Romain Larrieu.
It might have all been so different for the home side if Jamie Mackie had not missed an open goal at the end of the first half after Carl Fletcher's shot had been deflected to him.
The Pilgrims also hit the woodwork twice in the second half - through Rory Fallon in the opening minute after the break, and Gary Sawyer later on.
However, the Pilgrims, who had drawn their opening two Championship matches, saw Chopra double the Cardiff lead with ten minutes to go when he took advantage of a poor defensive header to steer the ball home.
He completed his hat-trick with five minutes to go, when Marcel Seip hauled down Chris Burke, firing home easily from 12 yards as Larrieu stood rooted to the spot.
Argyle belatedly reduced the arrears through substitute Alan Gow after ex-Home Park favourite Tony Capaldi handled the ball and was sent off for two bookable offences.
Gow, a first-half substitute for fellow new boy Cillian Sheridan, stroked the ball home past David Marshall but could not deny Cardiff their early-season status as Championship top dogs.
External Reports
Plymouth Official Website
Cardiff City Official Website
Wales Online
Plymouth Herald