Answer
is: concentration of hydrogen cations in lemon juice is 4.00 × 10−3 m.
pH
= 2.4.
pH
= -log[H₃O+].
[H₃O+] = 10∧(-pH).
[H₃O+] = 10∧(-2.4).
[H₃O+] = 0.004 mol/L.
pH value (potential of hydrogen - [H+]) is a logarithmic scale that
specify the acidity or basicity of an aqueous solution. When pH is greater than
seven, aqueous solution is basic, below seven is acidic and when pH is equal
seven, solution is neutral.
Carbon can make four bonds. Since it is doubly bonded carbon, it means it can make two more bonds. So, two more hydrogen atoms could help in bond formation.

Two H atoms are attached to each carbon.
<span>1. MgBr2
Soluble.
Rule: all the binary compounds of the group 17 (different to F) with metals are solubles, except those formed with Ag, Hg (I) and Pb.
2. PbI2
Insoluble.
Rule: it is one of the exceptions stated in the rule above.
3. (NH4)2CO3
Soluble.
Rule: salts containing NH4(+) are soluble.
4. ZnSO4
Soluble
Rule: </span><span>This salt is not an exception to the rule that most sulfate salts are soluble. Important exceptions to this rule include BaSO4,
PbSO4, Ag2SO4 and SrSO4
5. Sr(OH)2
Soluble (slightly soluble).
Rule: </span><span>Hydroxide salts of Group II elements (Ca,
Sr, and Ba) are slightly soluble</span>
Because I (iodide) is better leaving group than Cl, so it will leave when this molecule is reacted with strong base (sodium tert-butyl oxide) giving the elimination product provided in picture<span />