MCQ
Gold ore is concentrated by ……………
- ✓cyanide leaching
- Balkali leaching
- Cacid leaching
- Dhandpicking
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| Column - I | Column - II |
| A. $C _6 H _5 NO _2 \stackrel{ Sn / HCl }{\longrightarrow}$ | 1. $C _6 H _5 NHOH$ |
| B. $C _6 H _5 NO _2 \stackrel{ Zn / NH _4 Cl }{\longrightarrow}$ | 2. $C _6 H _5- N = O$ |
| C. $C _6 H _5 NO _2 \stackrel{ Fe / H _2 O _{( g )}}{\longrightarrow}$ | 3. $C _6 H _5- NH - NHC _6 H _5$ |
| D. $C _6 H _5 NO _2 \stackrel{ Zn / NaOH }{\longrightarrow}$ | 4. $C _6 H _5- NH _2$ |