Atmospheric pressure is measured with a barometer. A barometer consists of an evacuated vertical tube with its top end closed and its bottom end resting in a container of mercury that is open to the atmosphere The pressure exerted by the atmosphere acts on the exposed surface of the liquid to force mercury up into the tube. Sea level atmospheric pressure will support a mercury column generally not more than 29.92-in. high. Thus, the standard for atmospheric pressure at sea level is 29.92 in.-Hg, which translates to an absolute pressure of 14.69 psia.
The two basic reference points in all these measurements are standard atmospheric pressure and a perfect vacuum.
The unbalanced chemical equation with the corresponding phase for each substance is shown below:
Cu₍s₎ + H₂SO₄₍aq₎ → CuSO₄₍aq₎ + SO₂₍g₎ + H₂O₍l₎
The copper metal is solid, the sulfuric acid and copper sulfate are in aqueous solution. Water is in the liquid phase while sulfur dioxide is in the gas phase.
In order to obtain the balanced equation, we must ensure that the number of atoms present in the reactant side is equal to that in the product side. First, we list the elements involved and count their number on each side.
Reactant Product
1 Cu 1
2 H 2
1 S 2
4 O 5
To balance the equation, we need to have 2 moles of H₂SO₄ and 2 moles of H₂O. The balanced chemical equation is then:
Cu₍s₎ + 2H₂SO₄₍aq₎ → CuSO₄₍aq₎ + SO₂₍g₎ + 2H₂O₍l₎
Reactant Product
1 Cu 1
4 H 4
2 S 2
8 O 8
Your first step should be to analyse the compound. For example, if the compound is carbon, you know it always has a valence of four, so, if it has a formula C2H4 (ethylene) it obviously has a double bond. There are difficulties here because benzene C6H6 can be considered to have 6 1.5 C-C bonds, being aromatic.
A second step is to look at its structure. Double bonds are traditionally shorter than single bonds; triple bonds shorter still. Covalent bonds do have typical lengths, nevertheless you can still have problems.
<span>A third step is to consider reactivity. For example, if you have a C=C double bond, you can add, say, bromine to it Thus C2H4 gives C2H4Br2, and by adding two bromine atoms you know you have one double bond. Again, benzene becomes an awkward molecule, but because of this, you know benzene does not have double bonds in the traditional sense</span>
Answer:
(A) 
Solubility will increase.
(B) 
Solubility will decrease.
(C) 
Solubility will decrease.
Explanation:
a) According to Le Chatelier's Principle when a change is introduced in a reaction system at equilibrium, the system responds by the reaction shifting in the direction to counter the change introduced.
When the change introduced is addition of acid, some 
are consumed due to it and the system would respond by reaction shifting towards creation of more in the system by increased dissolution. Thus solubility increase.
(b) When are added, the reaction shifts to counter the change introduced of increased by shifting to side that decreases the increased . That happens by reaction shifting towards some 
precipitating back. Hence solubility decreases.
(c) The change introduced is addition of 
which will be countered by reaction shifting to side that decreases increased 
, which happens by some 
precipitating back. Hence solubility decreases.
