Which of the following is a positively charged Sol?

A sol is a colloidal suspension of very small solid particles in a continuous liquid medium. Sol particles typically have a charge that can be positive or negative, depending on the type of sol and the conditions of its preparation.

Among the options you provided:

• Starch - Typically, starch sols are negatively charged.
• Gum - Gum-based sols are generally not characterized by a specific charge without more context, but they are usually not particularly known for carrying a positive charge.
• Gold Sol - Gold sols are negatively charged. However, without specifying the stabilizing agent or the preparation method, we cannot definitively say it's positively charged. Historically, negatively charged gold sols are more commonly mentioned in literature due to the stabilizing agents commonly used.
• Blood is a positively charged colloid whereas sols of starch, gum & gold are negatively charged.