Answer:
4NaBr + 2CaF2 ---------- 4 NaF + 2CaBrz
Explanation:
Note: Although the video is not provided in this question, it is not needed to answer the question.
Answer:
B) It does not deflect at all
Explanation:
Since both half shells contain opposite charges, the two shells become electrically neutral when they are brought together and the electroscope discharges. On separating the two half shells again, the needle does not deflect because the half shells have now lost their charges to become neutral.
Answer:
a) Both blocks displace the same amount of water.
Explanation:
Specific gravity (S.G.) is a quantity that tells how much and object is submerged on water and is given by:

with ρ the densities
Density of water is
and density of aluminum is 
So:

A S.G. value bigger than one means the object is totally submerged so the water displaced is equal to the volume of the cube.
For the lead (density =
) block we're going to calculate specific gravity in this case:

Again S.G gravity is bigger than 1, so the lead block is totally submerged too, that implies the volume of water displaced is the volume of the block, that is the same volume as the aluminum block, so a is the correct one.