Question

que1 to get a sharp image of a far away object on the screen where the convex lens should be placed
que2 to get a blurred image of a far away object on the screen where the convex lens should be placed
que3 to get a slightly smaller blurred image of a far away object where the convex lens should be placed

Answer 1

The sharp image is formed when the screen is at the focus of the lens on the opposite side of the object. The blurness increases as we move the screen away from the focus and lens. So a more blurred image will be obtained when screen is placed at more distance from focus and a less blurred image will be obtained when the screen is at less distance from the focus.