If neutrons exert only attractive force, why don't we have a nucleus containing neutrons alone?

Highly energetic electron are bombarded in a target of an element containing 30 neutrons Tne ratio of nucleus to that of Helium nucleus is (14)^(1//3) . Find atomic number of the nucleus (R = 1.1 xx 10^(7) m^(-1) )

According to Newton's law of gravitation, if each body in the universe attracts every other body, why don't two bodies come towards each other?

According to Newton's law of gravitation. Equal forces exerted between earth and apple. The earth attracts an apple, the apple also attract the earth. If it does, why does the earth not 9 move towards the apple ?

Why do plants don't have respiratory organs ?

(a) Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have seen in Exercise 11.31, an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain. (m_(n) = 1.675 xx 10^(-27) kg) (b) Obtain the de Broglie wavelength associated with thermal neutrons at room temperature (27^(@)C) . Hence explain why a fast neutron beam needs to be thermalised with the environment before it can be used for neutron diffraction experiments.

Improvement in our lifestyle have resulted in generation of greater amount of waste material. We use more and more disposable things due to our changed lifestyle and wrong attitude. Why most of the wastes from our homes contain more and more non-biodegradable substances?

Two vessels have the same base area but different shapes . The first vessel takes twice the volume of water that the second vessel requires to fill upto a particular common height . Is the force exerted by the two water on the base of the vessel the same in the two cases ? If so , why do the vessels filled with water to that same height give different readings on a weighing scale ?