2[Au(CN)2]– + Zn \(\to\) [Zn(CN)4]2– + 2Au\(\downarrow\) is which of these
(A) Redox reaction
(B) Displacement reaction
(C) Combination reaction
(D) Decomposition reaction
The correct answer is A & B:
\[ 2[\text{Au(CN)}_2]^– + \text{Zn} \to [\text{Zn(CN)}_4]^{2–} + 2\text{Au} \]
This reaction involves the reduction of gold (\(Au\)) and the oxidation of zinc (\(Zn\)), making it a:
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
The equivalent resistance between the points \(A\) and \(B\) in the given circuit is \[ \frac{x}{5}\,\Omega. \] Find the value of \(x\). 
Method used for separation of mixture of products (B and C) obtained in the following reaction is: 
Minerals are the naturally occurring, homogeneous inorganic solid substances. They are having a definite chemical composition and crystalline structure, hardness and color. For example, copper pyrite, calamine, etc.

Impurities in an ore are called gauge. The removal of a gauge from the ore is called concentration ore.
Several steps are involved in the extraction of pure metal from ores. Major steps are as follows –