_______________ discovered that cathode rays have kinetic energy and raise the temperature of a metallic object on which they fall.
Goldsteirn
William crooke
Sir J.J thomson
Rutherford
Oxygen has_________ isotopes.
1
3
5
7
________________ proposed a theory of atom known as the atomic theory.
Democritus
John Dalton
Joseph Priestly
According to _______________ atomic theory,matter consists of small indivisible particles called atoms.
Rutherford.
Bohr.
Dalton.
Boyle.
According to _______________ atomic theory atoms are neither created nor destroyed.
Boyle's
Charals's
Bohr's
Dalton's
_________________ discovered electrons
Mendeleev
Sir J.J Thomson
Goldstein
________________ is the electrons in its valence shell forming an anion.
Oxygen
Chlorine
Nitrogen
Calcium
_____________ gains two electrons in its valence shell forming an anion.
_____________ gains three electron in its valence shell forming an anion with three negative charge.
Aluminium
______________ was an ancient greeck philosopher studied the nature of the matter and the basic constituents of all substance.
Joseph priestley
Boyle