Question: Which of these pairs of metal has variable valencies?

weight : 2

answer : Iron and copper

Zinc and caesium

Iron and strontium

Barium and scandium

question: J.J. Thomson’s model of the atom fell into disrepute and was replaced by one of the following

weight : 2

option : Dalton’s theory

answer : Rutherford Nuclear model

option : Bohr model

option : Balmer series model