If the mass of protons and neutrons is 1, then the mass of electron is

To find out number of neutrons in an atom, we need to know the

A. atomic number

B. proton number

C. electron number

D. mass number

The attraction of two ions due to opposite charge is known as

A. ionic bonding

B. covalent bonding

C. metallic bonding

D. dative bonding

To trace the path of phosphorus, the isotope of phosphorus which is added to the fertilizers, is

A. Phosphorus-31

B. Phosphorus-32

C. Phosphorus-33

D. Phosphorus-34

The name of physicist who discovered the nucleus of atom was

A. Democritus

B. John Dalton

C. Ernest Rutherford

D. Vander Waals

Sodium ion has

A. positive charge

B. negative charge

C. no charge

D. may be positive or negative