Answer:
Representative Elements
Explanation:
Representative elements are chemical elements of the long groups of the periodic table identified by the letter A, headed by the elements hydrogen, beryllium, boron, carbon, nitrogen, oxygen, fluorine and helium, as they appear in the periodic table of the elements. .
They are characterized by presenting "external" electronic configurations in their fundamental state ranging from ns1 to ns2np6, unlike the transition elements and internal transition elements.
The representative elements are the elements of groups 1 and 2 (block s), and of groups 13 to 18 (block p) .2 Until a few years ago, these groups were identified with Roman numerals from I to VII with the letter A.3 The elements of group 12 are generally considered as transition metals, however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and some scientists believe they should be included as representative elements or elements of the main groups.
Representative elements (with some of the lighter transition metals) are the most abundant elements on earth, in the solar system, and in the universe.
The representative elements are divided into eight groups and are characterized in that their electronic distribution ends in s-p or p-s. The group number results from adding the electrons in the sub-levels s or s and p of the last level.
Answer:
D. -120.9 kJ
Explanation:
According to Hess's law ,the total enthalpy change for a reaction is the sum of all changes regardless of the stages or the steps of the reaction.
....(1)
(this reaction should be reversed in order to reach the required reaction )
On reversing the reaction the sign of 
get reversed.
(In this case change sign from '-' to'+'. Hence = + 65 kJ)
....(1)
......(2)
Adding equation (1) and (2)
![Ca(OH)_{2} + 2HCl \rightarrow CaCl_{2} + 2H_{2}O[tex][tex]Delta H = - 186 + 65 = - 121\kJ](https://tex.z-dn.net/?f=%3Cstrong%3ECa%28OH%29_%7B2%7D%20%2B%202HCl%20%5Crightarrow%20CaCl_%7B2%7D%20%2B%202H_%7B2%7DO%3C%2Fstrong%3E%5Btex%5D%3C%2Fp%3E%3Cp%3E%5Btex%5D%3Cstrong%3EDelta%20H%20%3D%20-%20186%20%2B%2065%20%3D%20-%20121%5CkJ%3C%2Fstrong%3E)
(It is nearly equal to -120.9 kJ)
Answer:
The Californian red wine (pH 3.5) has a hydrogen concentration of 0.00032M
The italian white wine (pH 2.9) has a hydrogen concentration of 0.00126 M
Explanation:
<u>Step 1:</u> Data given
Wine 1 has a pH of 3.5
Wine 2 has a pH of 2.9
Wine 2 is more acid so should have more hydrogen ions
<u>Step 2:</u> Calculate hydrogen concentration
pH = -log [H+]
Wine 1: pH = 3.5 = -log[H+]
[H] = 10 ^-3.5 M = 0.00032 M
Wine 2: pH =2.9 = -log[H+]
[H+] = 10^-2.9 = 0.00126 M
The Californian red wine (pH 3.5) has a hydrogen concentration of 0.00032M
The italian white wine (pH 2.9) has a hydrogen concentration of 0.00126 M
The italian white wine has a higher concentration of hydrogen ions, what means it's more acid than the californian red wine.
The kinetic molecular theory of gases. May i have he brainiliest plz
