Answer is: Rutherford demonstrate that J.J Thompson's Plum Pudding model was not accurate.
Rutherford theorized that atoms have their charge concentrated in a very small nucleus.
This was famous Rutherford's Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles (helium atom particles, consist of two protons and two neutrons).
Rutherford observed the deflection of alpha particles on the photographic film and notice that most of alpha particles passed straight through foil.
That is different from Plum Pudding model, because it shows that most of the atom is empty space.
1. Cu + 2AgNO3 ==> 2Ag + Cu(NO3)2 ... balanced equation. This is both a single replacement reaction and an oxidation reduction reaction.
Moles of Cu present = 19.0 g Cu x 1 mole Cu/63.55 g = 0.2990 moles Cu
Moles AgNO3 = 125 g AgNO3 x 1 mole AgNO3/169.9 g = 0.7357 moles AgNO3
Which reactant is limiting? It will be Cu because the mole ratio is 2 AgNO3 to 1 Cu and there is more than enough AgNO3. Thus, amount of Ag formed will depend on moles of Cu (0.2990)
Moles of Ag formed = 0.2990 moles Cu x 2 moles Ag/mole Cu = 0.598 moles Ag
Mass (grams) of Ag formed = 0.598 moles Ag x 107.9 g/mole = 64.52 g = 64.5 g of Ag (3 sig. figs.)
Either NaI or INa are acceptable formulae for sodium iodide, which is indeed a binary ionic compound. So, the correct answer would be B.
The number 16 next to the elemental symbol of Nitrogen
which is N indicates the mass number of the element. Now the atomic number of N
is 7, this is also equal to the number of protons or electrons in the nucleus. So
the balance is 16 – 7 = 9 which is being occupied by the neutrons. Therefore
the number of neutrons is:
<span>9</span>
