Answer:
(a) No, every equation of line can't be written in slope Intercept form which can be explained in the following way.
→y=m x +c, where m is slope of line and c is y intercept.
Suppose a line is , ax +by+c=0
by=-ax -c

if, c=0, then line will be not in slope intercept form.
(b) NO,
Every line has two intercepts , one is called X intercept and another one is Y intercept.
Equation of line in Intercept form
ax +by+c=0
by+ax =-c

But if,c=0,equation of line can't be written in intercept form.
(c)
Yes, all lines which passes through Origin have no intercepts that is X intercept and Y intercept.
Equation of these lines are
y= mx, where m is slope of the line.