Obviously certain chords are easier than others. Check fingerings, and use open strings wherever possible. Remember that a viola section will play chords divisi unless otherwise instructed.

double stop

Double stops

Two strings sounded together. If the double stop is difficult (the left hand span is awkward) a section will play this divisi (notes shared out between instruments). Will work at any dynamic.

triple stop

Triple stops

Three strings sounded together. A section will normally play a triple stop divisi (i.e. notes shared out between instruments). On a solo instrument, triple stops only work at loud dynamics, otherwise they would be arpeggiated.
About triple stops:

quadruple stop

Quadruple stops

Four strings sounded, normally as an arpeggiation or broken chord. Four-note chords are no problem to a section if played divisi, but if non divisi then great care must be taken with left hand positions.
About quadruple stops:

arpeggiation

Arpeggiation

Arpeggiated triple or quadruple stop.

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