If you are talking about the Gold-foil experiment:
During Rutherford's time, the JJ Thomson (plum pudding) model was the accepted version of an atom. However when Rutherford shot positive alpha particle rays at a piece of gold foil. Some of the particles bounced back, meaning that Atoms had a positive center. Most of the particles went through, which means that Atoms are mostly empty space.
Answer: 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:

Answer:
In very hot, humid weather you might feel the air is heavier because moving around seems to take more energy than on dry days. Sticky days probably feel “heavier” because heat and high humidity slows the evaporation of perspiration, your body grows hotter and this saps your strength
Explanation:
Answer:
Calcium
Explanation:
Clacium has atomic number 20. The atomic number. This means that it has 20 protons and 20 electrons. it has 21 neutrons.