A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
He must have dipped the gold metal in the solution of aqua regia - $a$ $3:1$ mixture of conc. $HCl$ and conc. $HNO_3$. Aqua regia is a fuming, highly corrosive liquid. It dissolves gold in it. After dipping the gold ornaments in aqua regia, the outer layer of gold gets dissolved and the inner shiny layer appears. That is why the weight of gold ornament reduced.
Which metals do not corrode easily ?
Give reasons : Sodium, potassium and lithium are stored under oil.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Why do ionic compounds have high melting points ?
Differentiate between metal and non-metal on the basis of their chemical properties.