Classify the following sols according to theirs charges:
(a) gold sol (b) ferric hydroxide sol (c) gelatine (d) blood
(e) sulphur (f) arsenious sulphide (g) titanium oxide.

Explanation

To classify the given sols according to their charges, we will categorize them into positive and negative sols based on their properties.

### Step-by-Step Solution:

1. **Identify the Nature of Each Sol:**
- (a) **Gold Sol**: Gold sol is known to be a negatively charged colloid.
- (b) **Ferric Hydroxide Sol**: Ferric hydroxide sol is positively charged.
- (c) **Gelatine**: Gelatine is a negatively charged colloid.
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