A pair of dice is thrown simultaneously
$\therefore$ No. of total events $(n) = 6 \times 6 = 36$
Which are
$(1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6)$
$(2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6)$
$(3, 1), (3, 2), (3, 3), (3, 4), (3, 5), (3, 6)$
$(4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6)$
$(5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6)$
$(6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)$
$\therefore$ Event whose sum is a perfect square are $(1, 3), (2, 2), (3, 1), (3, 6), (4, 5), (5, 4), (6, 3)$
$\therefore m = 7$
$\therefore\ \text{Probability}=\frac{\text{m}}{\text{n}}=\frac{7}{36}$