I will assume that you mean "STP (Standard Temperature and Pressure)".
Since we know that "1 mole" of an ideal gas occupies "22.4 L" at "STP", then can establish the following relationships:
color(white)(------)color(orange)[("22.4 L")/("1 mole") or ("1 mole")/("22.4 L")
Knowing that, we can solve for the volume occupied by the helium gas,
(0.35 cancel"mole")/(1) * ("22.4 L")/(1 cancel"mole") = color(blue)"7.84 L"
as color(blue)"7.84 L"
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The answer makes sense because if "1 mole" occupies "22.4 L", then "0.35 moles" (roughly a third of the moles) will occupy a third of "22.4 L" ("if we round down 22.4 L to 21 L")
color(white)(--------)21/3 ~~"7 L"