A is
The image shows a logic gate symbol for an AND gate with inputs A and B, and output Y. The question asks to identify what "A" is, implying it's likely about the Boolean algebra expression or truth table for an AND gate.
The fundamental concept is the AND operation. The output Y is HIGH (1) only when both inputs A AND B are HIGH (1). In all other cases, the output is LOW (0). This is represented by the Boolean equation: .
Final Answer: The variable A represents one of the two inputs to an AND logic gate.
The given image shows a molecule with a benzene ring and a substituent. The substituent is a nitro group (-NO2) attached to the benzene ring. The question asks to identify the structure of compound A, which is the product of a reaction. The options are different structural isomers of dinitrobenzene.
When a nitro group is attached to a benzene ring, it is a meta-directing group due to its strong electron-withdrawing nature. This means that in electrophilic aromatic substitution reactions, the nitro group directs incoming substituents to the meta position.
Therefore, when nitration is performed on nitrobenzene, the second nitro group will attach at the meta position relative to the first nitro group. The product is 1,3-dinitrobenzene, or m-dinitrobenzene.
Let's look at the options:
The first option shows a structure with substituents at the 1 and 2 positions (ortho).
The second option shows a structure with substituents at the 1 and 3 positions (meta).
The third option shows a structure with substituents at the 1 and 4 positions (para).
The fourth option shows a structure that is not a simple dinitrobenzene isomer.
Thus, the correct structure for A, the product of nitration of nitrobenzene, is the meta-isomer.
Electrophilic Aromatic Substitution: This is a fundamental reaction where an electrophile replaces a hydrogen atom on an aromatic ring. The directing effects of existing substituents on the ring determine the position where the new substituent will attach.
Directing Groups: Substituents on a benzene ring are classified as ortho-para directing (activating) or meta-directing (deactivating) based on their electronic effects. The nitro group is a strong meta-directing deactivator.
While there is no specific formula, the key concept is the directing effect rule:
Ortho-para directors: -OH, -NH2, -alkyl, -OCH3, etc. (electron-donating groups).
Meta directors: -NO2, -CN, -SO3H, -CHO, -COOH, etc. (electron-withdrawing groups).
The compounds P, Q and S
were separately subjected to nitration using HNO3 / H2SO4 mixture. The major product formed in each case respectively, is
Match the reactions in Column I with appropriate options in Column II.
| Column-I | Column-II |
 |
(p) Racemic mixture |
 |
(q) Addition reaction |
 |
(r) Substitution reaction |
 |
(s) Coupling reaction |
|
(t) Carbocation intermediate |
Match the reactions in column I with appropriate types of steps / reactive intermediate involved in these reactions as given in column II
| Column-I | Column-II |
 |
(p) Nucleophilic substitution |
 |
(q) Electrophilic substitution |
 |
(r) Dehydration |
 |
(s) Nucleophilic addition |
| (t) Carbanion |