In a college five different subjects, viz. Physics, Chemistry, Botany, Zoology and Mathematics are taught on five different days of the same week, starting from Monday and ending on Friday. Is chemistry taught on Wednesday?
I. Two subjects are taught between Zoology and Mathematics. Mathematics is taught before Zoology. Chemistry is taught on the day immediately next to the day when Physics is taught. Botany is not taught on Friday.
II. Three lectures are scheduled between the lectures of Botany and Zoology. Mathematics is taught immediately before Physics.

I : In statement I alone, there is a gap of two classes between Maths and Zoology and Maths is taught earlier. Therefore, maths can be taught either on Monday or Tuesday.

case 1 : Maths on Monday, => Zoology will be taught on Thursday. Since, Phy and Chem are taught on consecutive days, they will be taught on Tue and Wed

respectively. This leaves us with Botany on Friday, which is not possible as per the question.

$$\therefore$$ this case is invalid.

case 2 : Maths on Tuesday, => Zoology will be taught on Friday. Since, Phy and Chem are taught on consecutive days, they will be taught on Wed and Thurs

respectively. This leaves us with Botany on Monday.

Thus, we have

Monday - Botany

Tuesday - Maths

Wednesday - Physice

Thursday - Chemistry

Friday - Zoology

Ans - No, chemistry is not taught on Wednesday.

Thus, I alone is sufficient.

II : Since, three lectures are scheduled between Botany and Zoology, these 2 will be taught on Monday & Friday with any subject on either day.

Maths and Physics are taught on consecutive days. Thus, maths can be taught either on Tuesday or Wednesday.

case 1 : Tuesday - Maths

Wednesday - Physics

Thursday - Chemistry

case 2 : Tuesday - Chemistry

Wednesday - Maths

Thursday - Physics

Thus, in both cases, Chemistry is not taught on Wednesday.

Thus, II alone is sufficient.