How I prepare the 1% Acid water

Is that 1% by weight (w/w) or 1% w/v(weight/volume) or 1% v/v (volume/volume)? Is the acid a solid or a gas or a liquid.

Assume a solid acid.
1% w/w. Dissolve 1 g acid in 99 g H2O.
1% w/v. Dissolve 1 g acid in enough water to form 100 mL solution.

If acid is a liquid.
1% v/v. Dissolve 1 mL liquid acid in enough water to form 100 mL solution