खुशी का पारा khuśhī kā pārā

का kā (hindi)

का denotes one of the under-mentioned relations between a Noun or a Pronoun and another Noun which follows the former. If the Noun that follows is Feminine (singular or plural), का changes to की; if it is Masculine and Plural, or has an oblique form, का changes to के.

• Possession and relationship.
• Material or composition.
• Worth and measure (space or time).
• Source, origin, cause.
• Subject (doer of an act).
• Object (of an activity).
• Part of a whole.
• Purpose.
• Characteristic.
  (A Basic Grammar of Modern Hindi)

खुशी خوشي khuśhī (persan)

Joy, delight, happiness.

पारा pārā (hindi)

Mercury.