The last one, answer is D
The correct answer is option B, that is, hypothesis.
A hypothesis refers to an anticipated illustration for an occurrence. It refers to a proposed illustration or a supposition made on the groundwork of inadequate proof as an initiation point for further investigation. In order for a hypothesis to be a scientific hypothesis, the scientific method needs that one can examine it.
The reaction is given by

Barium goes underneath beta decay to form Ceaseum
- Cs is very mellable element
- It can melt on your hand
Divide that my the molar mass which is 23 so 1.4087 g
Assuming that you’re looking for the concentration of water in the solution, then it would be 0.028 M.
You would have to use the formula:
c1v1 = c2v2, where c =concentration and
v = volume
C1 = ?
V1 = 250 mL
C2 = 0.2 M
V2 = 35 mL
C1 x 250 mL = 0.2 M x 35 mL
C1 = (0.2 M x 35 mL) / 250 mL
C1 = 0.028 M of water added to 35mL of 0.2M HCl
Therefore, there is 0.028 M of water added to 35mL of 0.2M HCl