2. Given two functions f(n) and g(n), if $g(n)=O(f(n))$ and $f(n)=O({n}^{2})$, then $g(n)=O({n}^{5})$.

3. Given two functions f(n) and g(n), if $g(n)=O(f(n))$ and $f(n)=O({n}^{2})$, then $g(n)=\mathrm{\Omega}(n)$.

I think the first one is false, but not sure about other two. Can anyone help me?