If each interior angle of a polygon is 144°; the number of sides in it is :

1. 5

2. 10

3. 6

4. 7

By formula,

Each interior angle of a regular polygon = $\dfrac{(2n - 4) \times 90°}{n}$

$\therefore \dfrac{(2n - 4) \times 90°}{n} = 144° \\[1em] \Rightarrow 180°.n - 360° = 144°.n \\[1em] \Rightarrow 180°.n - 144°.n = 360° \\[1em] \Rightarrow 36°.n = 360° \\[1em] \Rightarrow n = \dfrac{360°}{36°} = 10.$

Hence, Option 2 is the correct option.