Question: I am attempting to complete some *simple* homework examples my Russian teacher has given me. (I am learning Russian in my free time, whilst I work full-time)

The example given in my textbook is:

> 
> Given: Наша квартира была приватизирована пять лет назад.
> 
> 
> Desired: *Нашу квартиру приватизировали* пять лет назад.
> 
> 
> 

I require the following clarifications:

1. Is my assumption that the sentence is going from the *active voice* in the *given* sentence, to the *passive voice* in the *desired* sentence, correct?
2. What part of speech is the word *«приватизирована»*? (My usual search source, [Wiktionary](https://wiktionary.org) is failing me.)
3. What is happening to the above mentioned word when it moves from the *given* sentence to the *desired* sentence?
4. Why does the above mentioned word decline into the plural past tense form, whereas in the first sentence *«быть»* is in its feminine form?
5. How does it happen? What topic or topics must I read, to elaborate this topic further?
6. Are there any rules regarding this?

Answer: 
> 
> Наша квартира *была приватизирована* пять лет назад.
> 
> 
> 

The sentence is in the **passive voice** in the past formed with *быть* which agrees with the subject наша квартира in gender(feminine ) = была + приватизирована (past passive participle, short form) also agreeing in gender with the subject.The topic is *страдательный залог*.

> 
> Нашу квартиру приватизировали пять лет назад.
> 
> 
> 

The sentence is in the **active voice**, impersonal, past tense,formed with the verb which agrees with the "dummy" **they** (приватизировали), which is left out. The object is нашу квартиру (accusative sing).The topic is *безличные предложения*.
Both sentences mean the same and have a "hidden" agent.
> 
> Is my assumption that the sentence is going from the active voice in the given sentence, to the passive voice in the desired sentence, correct?
> 
> 
> 

Well, actually it's vice versa: passive to active.

> 
> What part of speech is the word «приватизирована»?
> 
> 
> 

This is "*краткое страдательное причастие*" (passive participle, short form, past tense, singular, feminine).

> 
> What is happening to the above mentioned word when it moves from the given sentence to the desired sentence?
> 
> 
> Why does the above mentioned word decline into the plural past tense form, whereas in the first sentence «быть» is in its feminine form?
> 
> 
> 

This is impersonate construction which is used along with "normal" active voice plural. I.e. "[they] did" (with "they" omitted) in Russian doesn't mean anyone in particular.