The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound
(a) is always negative
(b) is always positive
(c) may be positive or negative
(d) is never negative
Electric field is always directed from positive to negative. While dipole moment is always directed from negative to positive. So, it seems that dipole moment and electric field should always be in opposite directions. But in questions we come across that dipole moment is inclined at some angle to the direction of electric field. Why?
One of the following does not apply to a concave mirror. This is : (a) focal length is negative (b) image distance can be positive or negative (c) image distance is always positive (d) height of image can be positive or negative