$h =u \cos \theta t_2-\frac{1}{2} g t_2^2 \ldots(2)$
Equating (1) and (2) and substituting the value of $t_1$ and $t_2$ we get
$u \cos \theta=19.6 \;ms ^{-1}$
Maximum height $=\frac{u^2 \cos ^2 \theta}{2 g}=19.6 \;m$
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$(i)\, \square$$ (n, p) _{15} p^{32}$
$(ii)\, \square (p, \alpha){_8}O^{16}$
$(iii)\, _7 N^{14} (\square \,\, p) _6 C^{14}$
missing particle or nuclide (in box $\square$) in these reactions are respectively