For beta radiation, what stops its penetrating abilities?
aluminum

a piece of paper

skin

thin fabric

The correct answer is aluminium.

Beta radiation consists of electrons that are ejected by the nucleus. Beta particles have the charge of an electrons and the mass of an electron.  Beta particles are quite small , giving them the ability to travel through materials a bit longer before collisions with other particles makes them stop hence they can not be stopped by skin, a piece of paper and thin fabric. Their size accounts for why they have more penetration abilities than alpha particles which are large and can be stopped by a thin piece of paper. However, it is known that a few millimeters of aluminium sheet is able to stop beta particles.

The correct answer is aluminium.

може ли да зареждате повече информация, моля

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.