In an A.P. the value of the common difference d is
can be postive, negative or zero
always negative
always a natural number
always positive
In an A.P. the common difference can be positive, negative or zero.
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
Can force be negative or is it always positive??
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
Only one of the following applies to a concave lens. This is : (a) focal length is positive (b) image distance can be positive or negative (c) height of image can be positive or negative (d) image distance is always negative