Orthographic Projection Questions and Answers

Answer: C

Correct answer: both the assertion and the reason are true and the reason explains the assertion

Both are true and the reason is the whole justification. The same three views arranged the same way describe two different, mirror-image objects depending on which system is in use, and nothing in the geometry reveals which was intended. The symbol in the title block is therefore not a formality but the only thing that makes the drawing unambiguous.

Answer: D

Correct answer: the assertion is false although the reason offered is sometimes true

An additional view does sometimes convey further information, which is why it may be drawn at all. But views beyond the minimum clutter the sheet, cost drawing and checking time, and multiply the chances of two views disagreeing after a revision. The rule is the minimum number that describes the object completely, not the maximum that will fit.

Answer: A

Correct answer: keeps each hole's tolerance independent of the others

Measuring every hole from the same datum face means each position depends on one dimension and one tolerance, so an error in one does not displace any other. In a chain the errors accumulate, and the last hole carries the sum of them all. Datum dimensioning usually needs the same number of dimensions, not fewer, and tolerances must still be stated.

Answer: B

Parallel projectors perpendicular to the plane leave such a face undistorted, which is the whole utility of the method. Perspective converges and cabinet oblique deliberately halves the depth, so neither preserves size.