46. In fireworks, the green flame is produced because of
A. sodium
B. barium
C. mercury
D. potassium
47. Permanent hardness of water can be removed by adding
A. chlorine
B. washing soda
C. potassium permanganate
D. bleaching powder
48. Marsh gas is
A. nitrogen
B. ethane
C. methane
D. hydrogen
49. LPG consists of mainly
A. methane, ethane and hexane
B. ethane, hexane and nonane
C. methane, hexane and nonane
D. methane, butane and propane
50. Air is a/an
A. compound
B. element
C. electrolyte
D. mixture