The following numbers are expressed to the nearest whole number . Illustrate on a number line the range in which each must lie
(a) 7
(b) 40
(c) 0
(d) -200

Since that's your homework... and we don't do your assignments. What do you think the answer is and why?

Several of these examples as presented are ambiguous, so your answers will depend on the specific rules that have been presented either in your text or in your class on how to represent significant digits for integers that happen to end in one or more zeros. There is no single convention that cover these. To be more specific - does your text talk about marking trailing zeros with a bar, or underline, and/or a decimal point to indicate significance?