Answer : The correct option is, (D) CO₂, BCl₃, and Fe³⁺
Explanation :
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
(a) 
It is a Lewis-acid because it can accepts electron pairs.
(b) 
It is not a Lewis-acid because it can not accepts electron pairs but it is a base because it can donates and accept hydrogen ion.
(c) 
It is a Lewis-acid because it can accepts electron pairs because it has an incomplete octet and an empty 2p orbital.
(d) 
It is a Lewis-acid because it can accepts electron pairs.
Hence, the ions which behave as Lewis acids are, CO₂, BCl₃, and Fe³⁺
The elements are identified by the number of protons of the atom, which is its atomic number.
In this case the number of protons 39 (atomic number 39) permit you to identify the element as gallium.
Now, to identify the isotope you tell the name of the element and add the mass number.
The mass number is the sum of the protons and the neutrons
In this case, the number of neutrons is the original 39 plus the 2 added suddenly, i.e. 39 + 2 = 41, so the mass number is 31 + 41 = 72
Therefore, the isotope is gallium - 72.
Answer: isotope gallium - 72
So use equation: ΔH = MCΔT
M = mass of water
C = waters specific heat capacity (4.18)
ΔT = the temp. change of the reaction
ΔH = 100 x 4.18 x 10 = 4180J or 41.8KJ
so the cube absorbed 4180J of energy
hope that helps
The proper definition would be B. A mixture that can be separated.
