A shiny brown coloured element x on heating in air becomes black in colour name the element x and the blacked coloured compound formed

The tendency of the transition elements to form coloured compounds is attributed to

A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black coloured produce. Identify M and black coloured product and also explain the reaction M with oxygen.

Write the names and symbols of two most reactive metals belongiong to group I of the periodic table. Explain by drawing electronic structure how either one of the two metals reacts with halogen. With which name is the bond formed between these elements known and what is the class of the compuond so formed known? state any four physical properties of such compounds.

The blue colour of crystals of a substance changed on heating in a closed test tube but the colour was regained after some time on cooling. Name the substance and write its chemical formula. Explain the phenomenon involved.

Write the names of five elements which can make bond with carbon to form new compounds

An orange solid A on heating gives a colourless gas B. The gas B in dry conditions is Passed Over heated Ca to give a solid C. The solid C further reacts with water to Produce gas D which forms a blue coloured compound E on reaction with copper sulphate solution. Identify A, B,C,D,E and give the sequence of reactions involved .