Getting aggregate function needed error in sql query

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SQL

I have got a table

subjectname mark gender

maths 10 male

maths 20 female

physics 30 male

physics 40 female

chemistry 50 male

chemistry 60 female

i need to write an sql query to display the above table as follows

subjectname male female

maths 10 20

physics 30 40

chemistry 50 60 .How can i do this?

I tried the following query

select subjectname,case(gender) when 'male' then mark
else mark end  from Test1 group by(subjectname)

but got error

Msg 8120, Level 16, State 1, Line 1
Column 'Test1.gender' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Msg 8120, Level 16, State 1, Line 1
Column 'Test1.mark' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Msg 8120, Level 16, State 1, Line 2
Column 'Test1.mark' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.