Statement-I: If diameter of a sphere is decreased by 25%, then its curved surface area is decreased by 43.75%.

Statement-II: Curved surface area is increased when diameter decreases.

Statement-I: Let the diameter of sphere be 2r

Decreased diameter $=\left(2r-\frac{25}{100}\times 2r\right)=2r-\frac{r}{2}=\frac{3r}{2}$

Now diameter $=\frac{3r}{2}\Rightarrow radius=\frac{3r}{4}$

Curved surface area of sphere $=4\pi r^2$

New curved surface area $=4\pi {\left(\frac{3r}{4}\right)}^2$

Now, decreased in surface area $=\frac{4\pi r^2-4\pi {\left(\frac{3r}{4}\right)}^2}{4\pi r^2}\times 100\%=43.75\%$ .

Statement-II: If diameter is decreased, then curved surface area is also decreased.