Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. c. they always involve both a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

There are  3 types of chemical bonds:

1) Ionic: A bond formed by the transfer of electrons from from one atom to the other

2) Covalent : A bond formed by sharing of electrons between atoms

3) Metallic: A bond formed by the electrostatic attraction between metal ions and delocalised electrons.

Metals are electropositive, i.e. they have a tendency to lose electron. In a metallic lattice, this creates positively charged ions surrounded by negatively charged electrons which are held  by electrostatic forces of attraction.

Ans: E) They form because electrons move freely between atoms.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.