I have provided two images to help with this question. The first image is the reaction that is taking place. The γ-pyran is treated with the hydride acceptor triphenylmethyl perchlorate. A hydride is a hydrogen atom containing a lone pair of electrons giving it a negative charge. The triphenylmethyl cation is a positively charged carbocation that greatly wants to accept an electron pair to stabilize its charge. Therefore, it abstracts a hydride from the γ-puran starting material. It grabs one of the hydrogen atoms that is drawn in the reaction scheme. This results in the formation of triphenylmethane and a pyrylium perchlorate salt with the formula C₅H₅ClO₅. The important aspect of the structure is shown in the attached images. The most stable resonance form of the pyrylium cation is shown with a positive charge on the oxygen.
The reason this pyrylium ion is the most stable resonance form is because the formation of the oxonium ion (positive charged oxygen with 3 bonds) leads to an aromatic compound. There are 6 pi electrons in conjugation in this ring similar to a benzene ring and this results in the most stable structure.
Answer : The enthalpy change of reaction is 206.9 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given final reaction is,

The intermediate balanced chemical reaction will be,
(1)

(2)

First we will reverse the reaction 1 and 2 then adding both the equation, we get :
(1)

(2)

The expression for final enthalpy is,



Therefore, the enthalpy change of reaction is 206.9 kJ
Answer:
3.
Explanation:
There are four nitrogenous bases in a DNA including guanine (G), adenine (A), cytosine (C) and Thymine (T) and together they form the nitrogenous base sequence arranged in a specific order of three letters such as GAC and TAG to form a genetic code.
These nitrogenous base sequences forming genetic code are amino acid specific and determine the amino acid sequence in DNA. for example: CTT determines leucine and GTT determines valine.
Hence, the correct option is "3".
Answer:
8.72 × 10^5 moles
Explanation:
To find the number of moles in 5.25 x 10^29 molecules of sucrose, we divide the number of molecules by Avagadro constant (6.02 × 10²³ molecules). That is;
no. of moles = no. of molecules ÷ 6.02 × 10²³ molecules
In this case of sucrose, no of moles contained is as follows;
5.25 × 10^29 ÷ 6.02 × 10²³
5.25/6.02 × 10^ (29-23)
0.872 × 10^6
= 8.72 × 10^5 moles