ITMC 2018 Grade 9 National Preliminary set01 Question 1

Printed positive marks are preserved per question. The source uses different blank-answer and incorrect-answer rules by section, including an optional bonus penalty; the import does not reproduce that complete official scoring scheme.

Consider the ten real numbers $\sqrt0,\sqrt1,\sqrt2,\sqrt3,\sqrt4,\sqrt5,\sqrt6,\sqrt7,\sqrt8,\sqrt9$. How many are rational?