Question

M is an element in the form of powder .M burns in oxygen and the product obtained is soluble in water . The solution is tested with litmus .
1.) If M is a reactive metal then _____ will be evolved when M reacts with dil. Silphuric acid

Answer 1

1) If "M" is non metal then when dissolved in water gives acidic oxide.
We know acids turn blue litmus red

So the blue litmus will turn red while the red litmus remains the same.

2) If "M" is metal then it will form basic oxides. 
When dissolved in water it will form Alkalies.
A example --
4Na + O₂ -----> 2Na₂O
When Na₂O is dissolved in water,
Na₂O + H₂O ----> NaOH