Which statement about van der waals forces is true?
a)when the forces are weaker, a substance will have higher volatility.
b)when the forces are stronger, a substance will have lower viscosity.
c)when the forces are weaker, the boiling point of a substance will be higher.
d)when the forces are stronger, the melting point of a substance will be lower.

A

Explanation:

Van der Waals forces are the weak electric forces of attraction between molecules and their strength is dependent on the distance between the molecules. The longer the distance between the molecules the weaker the forces. Weaker Van der Waals forces mean that molecules can easily escape from the liquid  - hence meaning higher volatility.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-