Answer: 
Explanation:Bond energy of H-H is 436.4 kJ/mole
Bond energy of C-H is 414 kJ/mol
Bond energy of C=C is 620 kJ/mol
Bond energy of C≡C is 835 kJ/mol

= {1B.E(C≡C)+2B.E(C-H) +1B.E(H-H)} - {1B.E(C=C)+4B.E(C-H)}


Explanation:
Because a large amount of energy is required to break the strong inter-ionic attraction.
CaS => Ca2+ & S2-
Answer: Option (d) is the correct answer.
Explanation:
According to Bronsted-Lowry, species which donate a proton are known as acid. The species which accept a proton are known as a base.
In the given reaction, acids and bases are as follows.
HI +
+ 
Acid Base Conjugate acid Conjugate base
Therefore, the acid HI loses a proton to form a conjugate base that is
.
Thus, we can conclude that HI and
is an acid conjugate base pair.
Answer:
(R)-but-3-en-2-ylbenzene
Explanation:
In this reaction, we have a very <u>strong base</u> (<em>sodium ethoxide</em>). This base, will remove a hydrogen producing a double bond. We know that the reaction occurs through an <u>E2 mechanism</u>, therefore, the hydrogen that is removed must have an <u>angle of 180º</u> with respect to the leaving group (the "OH"). This is known as the <u>anti-periplanar configuration</u>.
The hydrogen that has this configuration is the one that placed with the <u>dashed bond</u> (<em>red hydrogen</em>). In such a way, that the base will remove this hydrogen, the "OH" will leave the molecule and a double bond will be formed between the methyl and the carbon that was previously attached to the "OH", producing the molecule (R) -but-3- en-2-ylbenzene.
See figure 1
I hope it helps!