Option 3- Avogadro's, Charles's and Boyle's
In order of reactivity: magnesium, iron, copper, silver
Number of moles of FeCl2 used = mass/ molar mass
Number of moles = 507/126.751 = 4.
If one mole of Fe reacts with two moles of sodium
Then 4 moles of Fe produces 8 moles of sodium.
Number of moles of sodium = mass/molar mass
Molar mass of sodium chloride = 23 +35.5 = 58.5 g/mol
Hence mass = 8 * 58.5 = 468 g. Hence Option A.
Answer: a)
: negative
b)
: positive
c)
: positive.
d)
: negative
e)
: positive.
f)
: positive.
Explanation:
Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.
is positive when randomness increases and
is negative when randomness decreases.
a) 
As ions are moving to solid form , randomness decreases and thus sign of
is negative.
b) 
As solid is changing to gas, randomness increases and thus sign of
is positive.
c) 
As 2 moles of reactants are converted to 4 moles of products , randomness increases and thus sign of
is positive.
d) 
As gas is changing to solid, randomness decreases and thus sign of
is negative.
e) 
As 7 moles of reactants are converted to 8 moles of products , randomness increases and thus sign of
is positive.
f)
As solid is changing to gas, randomness increases and thus sign of
is positive.
Answer:
C. water acts as a radiation shield to reduce the radiation level