Я не помню, чей это зонтик.

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Breakdown of Я не помню, чей это зонтик.

• это: this
• не: not
• зонтик: the umbrella
• чей: whose
• помнить: to remember

Questions & Answers about Я не помню, чей это зонтик.

What part of speech is чей, and how does it function in the sentence?

чей is an interrogative pronoun meaning “whose.” It introduces an indirect question about possession and agrees in gender, number, and case with the noun it modifies—in this case, зонтик (masculine singular nominative).

Why is there a comma before чей, and why does the sentence end with a period instead of a question mark?

Because we have an indirect question: Я не помню is the main clause, and чей это зонтик is a subordinate (embedded) question. In Russian, indirect questions are set off by a comma and take a period at the end, not a question mark.

What role does это play in чей это зонтик? Could I drop it?

это is a demonstrative pronoun (“this”), pointing to a specific umbrella. Without это, чей зонтик would simply mean “whose umbrella,” without highlighting “this one.” You can omit это if the context makes clear which umbrella you mean, but you lose the immediate “this is the one I’m asking about” sense.

How would you turn the embedded question into a direct question?

As a direct question you’d say: Чей это зонтик? (literally, “Whose is this umbrella?”), ending with a question mark and no comma.

Can I change the word order to Я не помню, это чей зонтик or Я не помню, чей зонтик это?

Yes. Both Я не помню, это чей зонтик and Я не помню, чей зонтик это are grammatically possible and understandable, though Я не помню, чей это зонтик is the most neutral and common word order for an embedded question.

If the noun were feminine or plural, how would чей change?

чей agrees with the noun’s gender and number in the nominative case. For example:

• Feminine (e.g. сумка): Я не помню, чья это сумка.
• Neuter (e.g. окно): Я не помню, чьё это окно.
• Plural (e.g. ключи): Я не помню, чьи это ключи.

Why use the nominative case for чей, rather than genitive with у кого?

There are two ways to ask “whose” in Russian:
1) With чей + noun in nominative, as in Чей это зонтик?
2) With у кого + noun in genitive, as in У кого этот зонтик?
The choice depends on style and emphasis. Чей-questions focus more on the possessive pronoun form, while у кого-questions use a locative construction (“at whom”). In your sentence, чей is used, so the noun and pronoun stay in nominative.