When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

Which of the following substances is a mixture?

If the quantity of oxygen occupying 2.76L container at a pressure of 0.825 atm and 300k is reduced by one-half, what is the pressure exerted by the remaining gas?

Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas? 

The products of the thermal decomposition of ammonium trioxonitrate(v) are?