In beta decay, a neutron is transformed into a proton via emission of an electron. This means that the total nucleon number remains the same; however, the proton number is increased by one (and the neutron number decreases by one). Therefore, the parent atom must also have mass number 99 but be of one less atomic number.
The atomic number of Tc is 43 and proton number 42 is Mo. Therefore, the answer is:
99Mo
The elements in this list are mercury, gold, iron, carbon and hydrogen. The compounds in this list, on the other hand, are sucrose, table salt, water and air. Elements are composed only of one substance while compounds are composed of two or more substances.
The change that would need to be made to the slit spacing in order to see a diffraction pattern is bending, because in understanding why light behaves like a wave, it is the interference and diffraction were the phenomena distinguish waves from particles but waves are the only one can interfere and diffract while particles do not. The light bends around obstacles or cylinder like waves do, then it is bending which cause and resulted in the single slit diffraction pattern.
