I know for number 4 the answer is c, sorry I can't help with the others.
A weak acid has a low concentration of H+ Ions and a dilute acid is a solution where acid is dissolved in a more volume of water than that of acid.
Depends on where the object is. On earth, moon , or somewhere without any other mass (theoretically). I think you mean how much does weigh on earth. So, the average gravitational acceleration on earth is : 9.83 m/s^2 To find out how much an object weighs, this is the formula : G=m.g where m is mass of the object g is the gravitational acceleration and G is weight. So, G = 10.9,83 = 98,3 N is the answer.
