Is Israel referred to as the pronoun 'she' in the Old Testament?
It is hard to look for a reference in the Old Testament. In the New Testament, Jerusalem, a city of Israel, was likened to Agar and Sarah and was referred in the feminine gender.
Galatians 4:21-31 KJV 21 Tell me, ye that desire to be under the law, do ye not hear the law? 22 For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman. 23 But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise. 24 Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar. 25 For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children. 26 But Jerusalem which is above is free, which is the mother of us all. 27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband. 28 Now we, brethren, as Isaac was, are the children of promise. 29 But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now. 30 Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman. 31 So then, brethren, we are not children of the bondwoman, but of the free.
In the Old Testament, when Israel worshipped idols and defied God, it was referred to as whore or harlot which at the time are mostly female.
Hosea 4:14-15 KJV 14 I will not punish your daughters when they commit whoredom, nor your spouses when they commit adultery: for themselves are separated with whores, and they sacrifice with harlots: therefore the people that doth not understand shall fall. 15 Though thou, Israel, play the harlot, yet let not Judah offend; and come not ye unto Gilgal, neither go ye up to Bethaven, nor swear, The LORD liveth.
There are several passages which employ the metaphor of marriage to describe the relationship between God and His people, and harlotry to describe the relationship between God' people and the false gods for whose sake they often left the worship of the Lord. In the Old Testament, Israel (the nation) is the wife and God is the husband. In these cases, Israel is referred to as she.
Since references were politely solicited, I will offer up Jeremiah, chapter 3, and most (if not all) of Hosea.