Nitrogen combines with metals to form

In Haber's process,hydrogen is obtained by reacting methane with steam in the presence of $NiO$ as a catalyst. This process is known as steam reforming. Why is it necessary to remove $CO$ when ammonia is obtained by Haber's process?

What is the $P-P-P$ bond angle in white phosphorus?

The oxide,which is neither acidic nor basic is

What is the appearance of red phosphorus?

In which of the following arrangements,the sequence is not strictly according to the property written against it?