Answer : The mass of oxygen formed must be 3.8 grams.
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The balanced chemical reaction will be,

According to the law of conservation of mass,
Total mass of reactant side = Total mass of product side
Total mass of
= Total mass of 
As we are given :
The mass of
= 25.3 grams
The mass of
= 23.4 grams
So,



Therefore, the mass of oxygen formed must be 3.8 grams.
Answer: If the gold in the crown was mixed with a less-valuable metal such as bronze of copper then this affects its density by making it to weigh even more and if it weighs more then it has less of chance to float. Observe: Drag each of the crowns into the liquid.
Explanation:
Answer:0.8742j/g°C
Explanation: SOLUTION
GIVEN
length of bar=1.25m
mass 382g
temperature= 20°C to 288°C
Q=89300J
Specific Heat Capacity will be calculated using
Q=mC∆T
where
C = specific heat capacity
Q = heat
m = mass
Δ T = change in temperature
C=Q/ m∆T
=89300/382X(288-20.6)
=0.8742j/g°C