Which subject does B tech ?

The information shall be represented as Name (Subject, Married/Unmarried, Gender)

From the given information, we can form the following conclusions:

1. C (Social Science, Married, _) and _(Chemistry, Married, _) are married to each other. The unknown person cannot be E or G.

2. A (Maths, Married, Male) and _(_, Married, Female) are married to each other. A cannot be the husband of C because he shall teach Maths, and not Chemistry. Also, A's wife cannot be G because his wife shall not teach Physics. Hence, G shall be unmarried.

3. E (Zoology, _, Female) and G (Physics, Unmarried, Physics) as per the given data.

Here, C's partner cannot be B either because he/she cannot teach chemistry while C's partner does. Further, F is unmarried. This leaves us with only one option for C's partner (Chemistry), which is D.

Therefore, C (Social Science, Married, Female) and D(Chemistry, Married, Male) are married to each other. The other couple has to be A (Maths, Married, Male) and E(Zoology, Married, Female) because there are only three females, E, G, and C, out of which G is unmarried and C is married to D.

As of now, we have the following data:

1. C (Social Science, Married, Female) and D(Chemistry, Married, Male) are married to each other.

2. A (Maths, Married, Male) and E(Zoology, Married, Female) are married to each other.

3. G (Physics, Unmarried, Female)

Now, F (_, Unmarried, Male) and B (_, Unmarried, Male). Now, B cannot teach Chemistry or Commerce. Hence, F shall definitely teach commerce.

Hence, the final point shall be: F (Commerce, Unmarried, Male) and B (_, Unmarried, Male). We cannot point out the subject taught by B because there is no data about it.