He had ________ one-rupee note.

• a
• an
• the
• zero article
Correct Option: A  [ a ]

Remark: the word "one-rupee" start with consonant sound. the sound of the first letter is 'w' not 'o'.

You should finish your work in _______ hour.

• the
• an
• a
• no article
Correct Option: B  [ an ]

Remark:

My mother is allergic to _______ cigarette smoke.

• a
• the
• an
• none of these
Correct Option: D  [ none of these ]

Remark:

The boy is studying in ____________ university.

• a
• an
• the
• zero article
Correct Option: A  [ a ]

Remark: "a" is used with "university" ( Vowel word with a consonant sound.)
similar: a one-act, a one-eyed, a one-man army, a union.

He is _________ cleverer of the two.

• a
• the
• an
• zero article
Correct Option: B  [ the ]

Remark:

It was ________ unit of measurement.

• the
• an
• a
• no article
Correct Option: C  [ a ]

Remark:

Our Principal is ________ man of principle.

• the
• a
• an
• No article required
Correct Option: B  [ a ]

Remark:

He met with __________ accident today.

• a
• an
• the
• zero article
Correct Option: B  [ an ]

Remark: The indefinite article "an" is used when word begins with a vowel sound.

He died without ________ heir.

• the
• an
• a
• no article
Correct Option: B  [ an ]

Remark:

Such _________ one was never seen before.

• a
• an
• the
• no article
Correct Option: A  [ a ]

Remark: "one" does not begin with a vowel sound; it begins with a consonant sound.