Answer: 2
Explanation:
To calculate the moles :

According to stoichiometry :
1 mole of
are produced by = 4 moles of 
Thus 1.18 moles of
will be produced by=
of 
Mass of 
Thus 85.0 g of
will be required and 2 steps are required to get the answer.
Answer: The black ball will have more mass than the white ball.
Explanation: Density of a substance is defined as the ratio of mass and volume occupied by the substance.
Mathematically,

We are given that the two balls are of same size, which means that the volume of both the balls are same. We are also given that the black ball is more dense than the white ball, which means that the black ball will have more mass.
As, 
Answer:
Exothermic reaction
Explanation:
Since in an exothermic reaction heat is released, the products will be more stable than the reactants.
22.3 is the answer to this question
Answer:
See Explanation
Explanation:
An endothermic reaction is one in which energy is absorbed and the change in enthalpy for the reaction is positive.
If we look at the reaction 2HgO + 45kcal ----> 2Hg + O2; we will notice that
i) 45kcal of energy was taken in (absorbed) for the reaction to occur
ii) The value of the reaction enthalpy is positive
For these two reasons, the reaction is an endothermic reaction as written.