First off chlorine is not a metal so you can ignore that one.
Sodium and Rubidium are in group 1 of the periodic table and Magnesium is in group 2.
Group one metals are more reactive than group two because it is harder for the group two metals to lose their 2 valence (outer most) electrons.
As you go down group 1 there is an increase in the reactivity this is because as you go down there is an increase in the atomic radius which leads to more shielding. This weakens the electrostatic forces of attraction making it easier to lose the outermost electrons, therefore they are more reactive.
Answer:
317 g
Explanation:
Cu + 2HCl --> CuCl2 +H2
1 : 2 1 : 1
1 mole of Cu = 63.5 g
1 mole of H2 = 2g
1 mole Cu produces = 1 mole of H2
63.5 g of Cu produces = 2 g of H2
So
10 g of H2 will be produced from = (63.5/2)*10 = 317 g of Copper
Scratching causes cracks and crevices on the surface of the flask (though microscopically). These will act as favorable sites for nucleation, which leads to the formation of crystals.
