1.the radius of curvature of a concave mirror is 30 cm.then 1)what is the focal length of the mirror? 2)mention the characteristics of the image,when the object is placed at 25cm,from the pole?3)where does the image form, when the object is placed at the centre of curvature?
2.in an element there are 29 electrons. then
1)what will be the outer most shell of the element?
2)write the valency of the element?
3)mention its atomic number?