Lots of nice examples in Chapter 2 of Eireks saga víðförla, which is
largely a series of questions and answers:
________________________________________________________

1. Eirekr mælti: "Hver er gröf sú, er þú mæltir, at í jörðu væri?"
Konungr segir: "Þat er jörð dauðans, er fyrir er búin syndugum
mönnum..."

E. said, "What is that pit which you said was in the earth?"
The king says, "That is the land of death which is prepared for
sinful people."

hver = feminine, agreeing with 'gröf sú'.
þat = neuter, even though 'jörð' is feminine.
_______________________________________________________

2. "Hverjar eru þær þrjár greiningar?"
"What are those three aspects?"

hverjar = fem.pl. of 'hverr'
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3. "Hverr er sá?"
"Who is that?"

Both masculine.
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But 'hvat er...?' introduces those questions where Eirek doesn't
know what gender the answer will be. Also used when someone does
know but is being a bit distainful. Both these examples refer to
people, the first from Arrow-Odd's Saga (Örvar-Odds saga), the
second spoken by Loki in the Eddic poem Lokasenna:

4. "Hvat er þat?" sagði Oddr.
"Þat er skjaldmær (f.), er lengi hefir mér fylgt," sagði konungr,

"What is that?" said Oddr.
"She's a shield-maiden who has been with me for a long time," says
the king,

5. hvat er þat it litla
"what is that little [puny] thing"
______________________________________________________

ON Online, 35 [ http://www.utexas.edu/cola/depts/lrc/eieol/norol-7-
X.html#Nor07_GP35 ], "In the later language 'er' is found combined
with the interrogative pronouns to produce relative pronouns, e.g.
hverr er '(he) who, whoever'; hvárr er 'whoever (of two)'; hvat(ki)
er 'whatever'; etc. This usage is an innovation in ON, imitative of
Latin."

I guess that applies to the following example from Eireks saga
víðförla, which was written (in this form at least) by a priest and
inspired by the Eleucidarius a collection of ecclesiastical lore
translated from Latin into Icelandic in the 12th century:

En til þess at ek fylli spurning þína, þá heyr þú, hvat er ek segi
þér, ok nem eptir.

But so that I may answer your question, hear what I say and learn.
_________________________________________________________
_________________________________________________________





--- In norse_course@yahoogroups.com, "llama_nom" <600cell@...>
wrote:

> Síðan gerði hann myrkvastofu; þat er þessi heimr, er vér byggjum.
> "Then he made a dungeon; that is this world which we inhabit."
> ('myrkvastofa' "dungeon" = feminine; þat = neuter; 'þessi
> heimr' "this world" = masculine).
>
> Þat er ómennska ef maðr gengr með húsum fyrir nenningarleysis

sakir

> eða ókosta annarra þeira er góðir menn vilja fyrir þeim sökum eigi
> hafa þau.
> "It is ''perversity'' if a person goes from house to house because
> of indolence or other failings which make good men unwilling to

have

> them."
> (A legal definition: 'ómennska' "perversity" = feminine).
>
> Þat er hin þriðja náttúra jarðar, þá er hon er opnuð ok grafin, þá
> groer gras á þeiri moldu er efst er á jörðunni.
> "That/this/it is the third property of earth, [that] when it is
> opened up and dug, grass grows on that soil which is uppermost on
> the earth."
> (þat = neuter; hin þriðja náttura = feminine; hon = feminine,
> referring to 'jörð' "earth".)
>
>
> Neuter also used as default where the reference is abstract and

not

> to any particular noun: 'þat er sagt' "it is said". Similarly

with

> adjectives. Here's a curious quote:
>
> ok er því gott góðu at trúa, en illt er at trúa illu, þótt satt sé
> "and so it is good to believe in good things, but bad to believe

in

> bad things, even if they are true" (!) [
> http://narrowshore.blogspot.com/2004/11/tt-satt-s-again-with-
> information.html ].
>
> With people, 'hverr' "who" may be used: 'Hverr er sá maðr, er svá

er

> spurull?' "who is that who is so curious/questioning?" (The

2nd 'er'

> here is the relative, the 3rd = "is".) But even when the

referrence

> is to a noun that is clearly animate and grammatically non-
> neuter, 'hvat' may be used together with the genitive plural:
>
> hvat er þat fiska?
> "what fish is that" (literally "what [one] of fishes").
>
> hvat er þat manna?
> "what man is that", "what sort of a man is that", "who is that"
>
> hvat manna ertu?
> "what sort of a man/person" are you", "who [exactly] are you"
> (the answer might include any or all of details such as name,
> lineage, status/occupation (king, beggar, etc.), place of origin,
> country ruled over, etc.)
>
> Also dat. sg. is possible: hvat er þat drykki? "what drink is

that"

> (what sort of a drink is that). But the genitive constrction

seems

> to be more common.
>