Which alloy is used for making aircraft parts?

What type of oxide is phosphorus pentoxide $(P_4O_{10})$?

Which gas has a pungent smell that causes choking and coughing?

Which of the following methods is $NOT$ a method for the refining of metals?

State reasons for the following:
$(i)$ Metals are good conductors of heat.
$(ii)$ Addition of some silver to pure gold for making ornaments.
$(iii)$ Inability of non-metals to displace hydrogen from dilute sulphuric acid.

Name two metals which react with dilute $HNO_{3}$ to evolve $H_{2}$ gas.