How to remove the ring? LEVEL 10 puzzle! #shorts

An electron in to be removed from the first energy level of hydrogen atom .How much energy is required for this purpose ?

From a complete ring of mass M and radius R , a 30^@ sector is removed. The moment of inertia of the incomplete ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is ,

A transverse section of the truck of a tree shows concentric rings which are known as growth rings. How are these rings formed ? What is the significance of these rings ?

How many pi electrons are there in a planar ring of phenol

From a circular ring of mass M and radius R, an arc corresponding to a 90^(@) sector is removed. The moment of inertia of the ramaining part of the ring about an axis passing through the centre of the ring and perpendicular to the plane of the ring is k times MR^(2). Then the value of k is

Three bells ring at intervals of 15,20 and 30 minutes.If they all ring at 10 'clock in thmorning together,at what time will they ring together again?