Water, mercury and bromine are similar to each other, because these three are _____ .

Valency of carbon is 4 and that of oxygen is 2. From this, we understand that there are ____ chemical bond/bonds between the carbon atom and one oxygen atom in the compound-carbon dioxide.

Identify the odd term out and explain.

Gold, silver, copper, brass.

Identify the odd term out and explain.
Hydrogen, sodium, potassium, carbon.

In one sample of brass, the following ingredients were found : copper $\left(70\right)\%$ and zinc $\left(30\%\right)$. Identify the solvent, solute and solution from these.