Question

Four students, (A), (B), (C) and (D) observed the colour and solubility of iron, sulphur and iron sulphide in carbon disulphide. The tick mark (✔) represents 'soluble', and cross mark (✕) represents 'insoluble', in carbon disulphide. Their observations are tabulated below.

Student	Colour			Solubility in carbon disulphide
	Fe	S	FeS	Fe	S	FeS
(A)	Yellow	Silvery	Greyish silver	(✔)	(✕)	(✔)
	Silvery	Orange	Reddish brown	(✕)	(✔)	(✔)
(B)
(C)	Grey	Yellow	Greyish black	(✕)	(✔)	(✕)
(D)	Silvery	White	Silvery white	(✔)	(✕)	(✕)

The student, who correctly reported the observations, is student :
(1) (A)
(2) (B)
(3) (C)
​(4) (D)

Answer 1

Iron is of grey colour and sulphur is of yellow colour. When iron and sulphur react they form black coloured iron sulphide.
Sulphur is only soluble in CS₂ solution. So, out of four students, only student C correctly reported the observation.

Hence, the correct answer is option 3.